ENBased on archival documents of the former KGB office in Soviet Lithuania the work of the latter in the field of recruitment of its secret informers among Catholic clergy and efforts with their help to infiltrate the Vatican, to influence its decision making in ecclesiastical affairs is investigated in the article. The most important questions addressed in the article are: how successful were Soviet state security organs in promoting to leading positions in Church administration recruited local clergymen and if they managed to turn those agents into an effective tool to influence the Vatican and Lithuanian exile clergy. There are particular operations of KGB of Lithuanian SSR directed at the Vatican, which were more closely described in the article: efforts to use priests as agents, who came to study at Pontifical universities in Rome, sending of recruited clergymen to represent Lithuanian Catholic Church at the II Vatican Council, aspirations to employ agents from the ranks of clergy to follow at and to influence actions of the pope John Paul II during the 1980s. Based on the research of those cases the conclusion is made that KGB of Lithuanian SSR, in spite of large efforts in this direction and even more large expectations in Moscow on the matter, wasn’t able to create effective channels to get valuable intelligence materials on the Vatican and to impact its decisions. Keywords: Lithuanian Catholic clergy, the Vatican, Soviet anti-religious policy, employment of agents of KGB abroad.