AbstractBackground We aimed to determine the prevalence and gap in use of mental health services for late-life depression in four European regions (Western Europe, Scandinavia, Southern Europe and Central and Eastern Europe) and explore socio-demographic, social and health-related factors associated with it.Methods We conducted a cross-sectional study based on data from the Survey on Health, Ageing and Retirement in Europe. Participants were a population-based sample of 28 796 persons (53% women, mean age 74 years old) residing in Europe. Mental health service use was estimated using information about the diagnosis or treatment for depression.Results The prevalence of late-life depression was 29% in the whole sample and was highest in Southern Europe (35%), followed by Central and Eastern Europe (32%), Western Europe (26%) and lowest in Scandinavia (17%). Factors that had the strongest association with depression were total number of chronic diseases, pain, limitations in instrumental activities of daily living, grip strength and cognitive impairment. The gap in mental health service use was 79%.Conclusions We suggest that interventions to decrease the burden of late-life depression should be targeted at individuals that are affected by chronic somatic comorbidities and are limited in mental and physical functioning. Promotion of help-seeking of older adults, de-stigmatization of mental illness and education of general practitioners could help decrease the gap in mental health service utilization.