From 1983–1994 a community mental health programme was set up in Guinea-Bissau. The first part of the programme concentrated on epidemiological aspects: rural and urban study areas were selected on socio-economic level and participation in the liberation war. A two-stage design was used to screen 351 adult consecutive general health care attenders and 100 children in a rural and an urban area for mental disorder. Psychiatric disorders have a morbidity of 12% among adults seen in Primary Health Care. Disorders were mainly neuroses (74%), but more psychoses were found than in other countries. No statistically significant difference in morbidity was found between rural-urban areas or between previous war and non-war zones. The diagnostic sensitivity of the Primary Health Care workers was 31%, their diagnostic specificity 88%. Thirteen per cent of the children showed neuropsychiatric disturbances. There were no sociocultural impediments to this public mental health approach. During the following intervention programme 850 Primary Health Care workers were trained and supervised nationwide. The diagnostic sensitivity of major mental disorders and epilepsy increased from 31% to an average of 85%. Before the training, their knowledge of the treatment of these disorders was nil whereas after training 82% of the patients received appropriate treatment. Moreover, this model programme shows a profitable cost/benefit ratio and a high sustainability over the last 10 years.