He had undergone quintuple heart bypass surgery in November 1996 but continued to suffer from a series of other ailments. Two months after his heart surgery, he contracted pneumonia. Although he recovered, his health remained a constant issue. He also had long-running back trouble, and seemed increasingly shaky, both physically and mentally.
After his dramatic exit from government in 1999, Yeltsin appeared rarely in public, except for an occasional official ceremony, holiday reception or tennis tournament.
Born Feb. 1, 1931, to a peasant family in the Sverdlovsk region of western Russia, Boris Nikolayevich Yeltsin won Russia's first popular presidential election in a landslide in June 1991. Russia still was part of the Soviet Union, but the central government had started ceding power to the 15 republics.
In the final years of his leadership, Yeltsin often seemed out of touch. He retreated regularly to his country residence outside Moscow and stayed away from the Kremlin for weeks at a time. Then on New Year's Eve 1999, he stunned Russia and the world with his resignation -- having given no hint that he would step down before his second term was up in spring 2000. Yeltsin named his last prime minister, former KGB agent Vladimir Putin, acting president.
"Russia must enter the new millennium with new politicians, with new faces, with new, smart, strong, energetic people," Yeltsin said. "And we who have been in power for many years already, we must go."
U.S. Secretary of Defense Robert Gates, in Moscow for talks about a proposed anti-missile system in Europe, called Yeltsin "an important figure in Russia's evolution toward democracy."
Yeltsin is survived by his wife, two daughters and several grandchildren. Funeral plans were yet not announced by Monday morning.