MOSCOW - In his nearly two decades at the head of the world's largest Orthodox church, Patriarch Alexy II oversaw a religious revival in Russia and healed a major church rift, but his death leaves a long-running dispute with the Vatican unresolved.

Alexy's death yesterday at age 79 deprives the Russian Orthodox Church of its dominant figure, whose stern, bearded mien gave him an almost medieval aura of inflexible righteousness. He often complained that Roman Catholics were poaching adherents among a people who traditionally would have been Orthodox if atheistic Soviet rule had not impeded them.

Yet he and the church held many discussions with the Vatican, aiming to reach an agreement that would allow the church to accept a papal visit to Russia.

Without Alexy at the helm, the church's initiatives on that question may go dormant for several months. The church's Holy Synod is to choose a placeholder leader today, but election of a new patriarch is likely to take six months. Metropolitan Kirill, the church's foreign relations chief who has had extensive contact with the Vatican, appears to be one of the top candidates.

The Moscow Patriarchate said Alexy died at his residence outside Moscow, but did not give a cause of death. Alexy had long suffered from a heart ailment, although on Thursday he had appeared comparatively well while conducting services. *