Background. This paper describes the 12-month prevalence, severity and demographic correlates of 16 DSM-IV psychiatric disorders and service utilization in the Mexican urban population aged 18–65 years of age. This is representative of 75% of the national adult population.

Method. The sample design was a strict probability selection scheme. The response rate was 76·6%. The World Mental Health Survey version of the Composite International Diagnostic Interview was installed on laptops and administered by lay interviewers. An international WHO task force carried out its translation into Spanish.

Results. The 12-month prevalence of any disorder was 12·1%. The most common disorders were specific phobia (4·0%), major depressive disorder (3·7%) and alcohol abuse or dependence (2·2%). The 12-month prevalence of very severe disorders was 3·7% of which only 24% used any services. Age was the only variable associated with any 12-month disorder, with the younger more likely to report any disorder. Income was associated with severity, with low and low–average incomes more likely to report a 12-month disorder. Females were more likely to report a mood and anxiety disorder, but less likely to report a substance disorder. The group of separated/widowed/divorced was more likely to report a mood and an impulse-control disorder.

Conclusions. The results show that while psychiatric disorders are common in the Mexican population, very severe mental disorders are less common and there is extreme under-utilization of mental health services.