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.