Background: As a part of the World Health Organization multicentric study of emotional disorders in general medical care, we studied patients who had a chronic medical ailment and a psychiatric disorder, according to ICD-10. Aim: To report the prevalence of patients with coexisting medical and psychiatric disorders. Patients and methods: All patients, aged 15 to 65 years old, consulting in primary care outpatient clinics, were interviewed using a general health questionnaire. In a second phase, patients with chronic medical disorders were subjected to the World Health Organization Composite International Diagnostic Instrument. Results: Sixty nine percent of interviewed Chilean patients had a medical condition, compared to 60,3% of the global study group. Of these, 66% had a coexisting psychiatric diagnosis, compared to 31% of the global study group. The most frequent diagnoses in the Chilean sample were somatization disorders in 25%, harmful alcohol use in 14%, depression in 35% and hypocondriasis in 6%. There was a higher prevalence and odds ratio for psychiatric diagnoses among Chilean women. Conclusions: Patients with chronic medical disorders should be considered a high risk group for the coexistence of psychiatric disturbances. (Rev Méd Chile 2000; 128: 729-34).