Psychiatric morbidity among 505 attenders on a single day at 32 general practices in South Verona was assessed using the General Health Questionnaire (GHQ-30) and recordings of practitioners' evaluations. The usual GHQ scoring system with a cut-off point of 5/6 resulted in 52% of high-scorers while the scoring system for longstanding psychological distress conditions (C-GHQ) yielded 37% of high-scorers (cut-off point 11/12). General practitioners identified 28% of attenders as cases. One-day population based prevalence estimates for the GHQ-30 and practitioners' assessment gave values of 6.6 and 4.5 per 1000 at risk. Among several possible risk factors, only presence of previous psychiatric illness increased significantly the relative risk of being a case in terms of GHQ, C-GHQ scores and practitioners' assessments. These findings are discussed in relation to the results of other surveys in the same area and other general practice studies.