The activities of a consultation-liaison psychiatry service to general medical units in a university affiliated suburban teaching hospital are described, with a report from the MICRO-CARES clinical database on 165 consecutive referrals over a 12 month period. The referral rate was 4.2% of admissions. The data confirm the association of psychiatric referral and prolonged length of hospital stay (mean of 18 days for referred patients, 9 days for non-referred patients). The most common reasons for referral were depression, suicide risk evaluation, organic brain syndrome and suspected psychological component to illness. The most common psychiatric diagnoses were Mood Disorders (55%), Organic Mental Disorders (35%), Adjustment Disorders (19%), Somatoform and other Somatic Disorders (16%) and Personality Disorders (15%). Although 67% of patients received at least one confirmed diagnosis, 39% of all diagnoses remained "differential", or unconfirmed, at discharge. Concordance with drug recommendations was 97% and with non-drug recommendations 95%. Two groups of patients were prominent among the referrals: the young self-poisoning patient, and the older patient living alone. The issues involved in providing a liaison psychiatry service to general medical units with these characteristics are described.