Background Except for dementia and depression, little is known about common mental disorders in elderly people. Aims To estimate current, 12-month and lifetime prevalence rates of mental disorders in different European and associated countries using a standardised diagnostic interview adapted to measure the cognitive needs of elderly people. Method The MentDis_ICF65+ study is based on an age-stratified, random sample of 3142 older men and women (65-84 years) living in selected catchment community areas of participating countries. Results One in two individuals had experienced a mental disorder in their lifetime, one in three within the past year and nearly one in four currently had a mental disorder. The most prevalent disorders were anxiety disorders, followed by affective and substance-related disorders. Conclusions Compared with previous studies we found substantially higher prevalence rates for most mental disorders. These findings underscore the need for improving diagnostic assessments adapted to the cognitive capacity of elderly people. There is a need to raise awareness of psychosocial problems in elderly people and to deliver high-quality mental health services to these individuals.