Cigna is an American worldwide health services organization based in suburban Hartford, Connecticut. Its insurance subsidiaries are major providers of medical, dental, disability, life and accident insurance and related products and services, the majority of which are offered through employers and other groups (e.g. governmental and non-governmental organizations, unions and associations).

Cigna offers Medicare and Medicaid products and health, life and accident insurance coverages primarily to individuals in the U.S. and selected international markets. In addition to its ongoing operations described above, Cigna also has certain run-off operations, including a Run-off Reinsurance segment. In the Phoenix metropolitan area, Cigna runs a full-service staff-model HMO (health maintenance organization) with satellite clinics throughout the region, known as the Cigna Medical Group.

Cigna Global Health Benefits also operates under the Cigna corporation. Their tag line is 'Together, all the way.'

Cigna was formed by the 1982 merger of the Connecticut General Life Insurance Company (CG) and INA Corporation (the parent corporation of Insurance Company of North America, the first stock insurance company in America). Insurance Company of North America was formed in 1792 and is therefore a corporate ancestor of Cigna. The CG was created in 1865 by a special act of the Governor of Connecticut. In October 1871, the great Chicago Fire burned for two days, destroyed 2,000 acres and left 100,000 people in Illinois homeless. INA paid $650,000, one of only 51 insurance companies (out of a total of 202) to pay claims in full.

Before selling its domestic and international property and casualty business to the Bermuda-based ACE Insurance company in the late 1990s, Cigna was among the companies with a large international network comparable to those of AIG, Allianz, and Zurich. The strategy behind the sale was to concentrate on core business. ACE – at that time a key player at the Bermuda and Lloyds insurance market – on the other hand was interested on expanding the international network in the traditional insurance market.

Cigna sold the majority of its life insurance operations to Lincoln National Corporation in 1997. Cigna now operates in 30 countries, has approximately 35,800 employees and manages around US$53.734 billion in assets.

In 2002, it was alleged in violation of the Securities Exchange Act for earnings manipulation. Its common stock price plummeted significantly as a result. In October 2011, Cigna agreed to buy HealthSpring Inc. for $3.8 billion to jump-start its business selling Medicare plans from 46,000 Medicare Advantage members to almost 400,000 Medicare Advantage members. The payment would come from an issue of new equity to cover about 20 percent of the value, with the rest funded by additional cash and debt.

In June 2015, U.S. health insurer Anthem Inc. announced an offer to acquire Cigna for more than $47 billion in cash and stock. Anthem confirmed it had reached a deal to buy Cigna on July 24, 2015. On July 21, 2016, the US Justice Department filed an antitrust suit to block the proposed merger, and a District Court ruling on February 8, 2017 blocked the merger on anticompetitive grounds. That month, Cigna Corp. called off its $48 billion merger agreement with Anthem Inc., with Anthem stating it would "continue to enforce its rights under the merger agreement and remains committed to closing the transaction."

Cigna Global Health Benefits is a business unit within Cigna. The company is headquartered in Wilmington, Delaware, close to Philadelphia. Additional Cigna Global Health Benefits operations are located in Visalia, California, and Greenock, Scotland and Shanghai, China and Antwerp, Belgium. Sales offices are located in North America, Europe, Asia and the Middle East.

CGHB global health plans typically include medical, dental, behavioral and disability, as well as business travel and life components. Expatriates are defined as employees of multinational companies working outside their home country on short, and long-term international assignments. CGHB maintains its own, in-house international claims platform, and offers a network of physicians and hospitals for its members (including 550,000 in the U.S. and more than 141,000 outside the U.S.).

In December 2007, Cigna was criticized after the company refused to pay for a liver transplant of a California teenage girl, Nataline Sarkisyan, justifying their refusal to pay by claiming that the procedure was experimental, even though there was a liver ready and waiting to be transplanted and doctors estimated she had a 65% chance of surviving at least six months. In response to much protest and public scrutiny, Cigna reversed its decision, though Ms. Sarkisyan died awaiting the transplant. Cigna notes that it had no financial stake in the decision to authorize the transplant because it merely administers the insurance plan of Mr. Sarkisyan's employer and would not bear the cost of any operation. However, Cigna offered to pay for the transplant itself when it made the exception to the policy.

Even though liver transplants have been performed since 1963 and are a well accepted treatment option for end-stage liver disease and acute liver failure, Cigna defended its actions by claiming that there was insufficient data to show that a transplant for a patient in Sarkisyan's condition would be safe and effective. The California court agreed with Cigna’s position that the Sarkisyans’ claims regarding Cigna's decision-making were preempted by federal ERISA law. On April 16, 2009, the United States District Court for the Central District of California dismissed all of the claims against Cigna related to the coverage determination.

In 2011, the California Nurses Association determined that Cigna denies roughly 39.6% of all claims (compared to competitors such as Aetna who denied about 5.9% of all claims in the same time frame).

In August 2012, Cigna fought and lost their argument in court that ABA therapy for autistic children is "experimental". The courts decided the therapy is a known treatment for autistic children, and Cigna’s arguments had no merit. As of 2011, Cigna was fighting to have this decision reversed.

On February 9, 2005, CIGNA elected to adopt in the fourth quarter of 2004 fair value accounting for its stock options in accordance with SFAS No. 123 and to restate prior periods.

The UK newspaper Guardian in their Esc and Ctrl videoblog about control of the Internet by corporations, documented an incident with Nataline Sarkisyan and the former vice president of Cigna talking about astroturfing, the practice of creating fake blogs by interested groups, e.g. health insurance companies, to push claims that are profitable for said company into media, e.g. dismissing universal health care.

Cigna spent more than $4.4 million from 2005 to 2009 on lobbying to attain legislation that the company favors. This includes $720,000 spent in 2009 alone, when it had 20 lobbyists at five firms working on their behalf.

In 2008, the head of Cigna's public relations, Wendell Potter, resigned, becoming a whistleblower who gave testimony in 2009 to the U.S. Senate Committee on Commerce, Science and Transportation in favor of reform of the health care industry.

Cigna received gold in the 2009 Gartner & 1to1 Customer Experience Excellence Award. The awards are given to the companies that "most clearly demonstrate exemplary customer relationship strategy and an unrivaled level of excellence in delivering the customer experience".

In January 2010, Cigna received the JD Power award for customer service for all of its call centers for the fourth time in a row.

In 2008, the Cigna Foundation contributed $2,533,535 to charitable activities that promote wellness. Since 1995, Cigna and its employees have contributed $22.3 million to the March of Dimes.

In July 2010, Cigna began giving each company employee eight hours of paid time off annually to volunteer with non-profit health and community service organizations. The Salvation Army of Greater Philadelphia helped kick off the program in front of Cigna's Philadelphia headquarters with the Christmas in July campaign.

On April 16, 2010, Cigna announced an alliance with Humana group to offer a streamlined Medicare Advantage offering through employer clients for retirees.

In November 2011, Cigna and TTK Group, an Indian business conglomerate focused on healthcare, formed a joint venture called Cigna TTK to develop a health insurance business in India subject to obtaining government approvals.