A two-level community study was carried out among the Peul and Dogon populations of the Bandiagara plateau (Mali). For the purpose of the study the Questionnaire pour le depistage en santé mentale (QDSM), a 23-item screening questionnaire derived from the Self-Reporting Questionnaire (SRQ), was adapted and validated; internal consistency and accuracy were evaluated. In the first phase of the study, 466 subjects randomly selected on a residential basis were evaluated by means of the QDSM. In the second phase all subjects who were "positive" at the screening, as well as a sample who were "negative", were examined by means of a semistructured interview. When necessary, clinical and laboratory investigations were performed. The estimated prevalence of psychiatric cases was 6.4%. A significant risk was associated with age and education. Somatic diseases frequently associated with psychiatric disorders were genitourinary tract disorders, tuberculosis and disabling cardiopathies. The main factor determining the seeking of medical help either through traditional of conventional health systems was the presence of a somatic disorder. The presence of a true minor psychiatric disorder, however, was often associated with divining practices.