Background There have been relatively few surveys in Latin America that have attempted to estimate the prevalence of psychiatric morbidity in private households. Aims To determine the prevalence of common mental disorders and socio-demographic correlates among adults from Santiago, Chile. Method Cross-sectional survey of private households with a probabilistic sampling design was used. Common mental disorders were measured using the Clinical Interview Schedule—Revised (CIS—R). Results Three thousand eight hundred and seventy adults were interviewed. Twenty-five per cent were CIS—R cases and 13% met criteria for an ICD-10 diagnosis. Low education, female gender, unemployment, separation, low social status and lone parenthood were associated with a higher prevalence. Conclusions Prevalence rates were higher than those found in urban areas of Great Britain, both for ICD-10 diagnoses and ‘non-specific neurotic disorders’. Similar socio-demographic factors were associated with an increased prevalence of common mental disorders in Chile as in the UK. There is a need to unify methodologies to be able to compare results internationally.