Background: The Diagnostic and Statistic Manual (DSM) solved the problem of diagnostic criteria for psychiatric diseases. Highly structured interviews such as Composite International Diagnostic Interview (CIDI) allow the evaluation of psychiatric disorders in large samples, whith great accuracy. Aim: To report the prevalence rates of psychiatric disorders in a representative sample of Chilean individuals. Material and methods: The CIDI was administered to 2978 Chilean individuals coming form four provinces. Lifetime and prevalence rates of psychiatric disorders, based in the third revision of the DSM, were calculated. Results: Thirty six percent of the population had a psychiatric disorder at least once in their lifetime and 23% had a disorder in the last six months. The most common lifetime diagnoses were agoraphobia in 11%, major depressive disorders in 9%, dysthymia in 8% and alcohol dependence in 6%. Only 49% of those with a psychiatric disorder sought medical care, while 4% of those individuals considered devoid of psychiatric illnesses, consulted in a mental health facility. Conclusions: The prevalence of psychiatric disorders in the Chilean population is similar to that of other Spanish speaking populations in Latin or North America (Rev Méd Chile 2002; 130: 527-36)