Apical periodontitis is prevalent in many Western populations and is frequently detected in connection with inferior quality of endodontic treatment. However, information about endodontic conditions from eastern European countries is limited. The aim of the present investigation was to study the prevalence of apical periodontitis and the quality of endodontic treatment in 35-44-year-old Lithuanians. The prevalence of apical periodontitis was 70%. An overall success rate of 65% was found for root-filled teeth while 56% of pulp amputations (pulpotomies) were considered successful based on a radiographic evaluation. The quality of the root fillings showed little impact on the treatment results, except for over-extended fillings, which were associated with a high number of failures.