This study reports the factor structure of the symptoms comprising the General Health Questionnaire when it is completed in a primary care setting. A shorter, 28-item GHQ is proposed consisting of 4 subscales: somatic symptoms, anxiety and insomnia, social dysfunction and severe depression. Preliminary data concerning the validity of these scales are presented, and the performance of the whole 28-item questionnaire as a screening test is evaluated. The factor structure of the symptomatology is found to be very similar for 3 independent sets of data.