This paper reports a 5-year experience of a surgical day case unit. Over 10,000 patients were treated in the three specialties of gynaecology, orthopaedics and general surgery. Seventy patients (0.7%) were admitted to the inpatient beds of the hospital directly from the day case unit. These patients were reviewed to determine if any avoidable factors had played a part. Two-fifths of the admissions after suction termination of pregnancy were of patients of more than 12 weeks' gestation. Admission was necessary on 10 occasions after orthopaedic and general surgical operations when the procedure was too extensive or too painful to allow the patient to be discharged home. Complications of anaesthesia, either local (n = 5) or general (n = 15), constituted the largest cause for admission. Postoperative nausea, vomiting and drowsiness became less frequent after a change in technique to the use of a short-acting anaesthetic agent (12 in the 3 years before; two in the 2 years after). Day case surgery is safe and should rarely be followed by the need for hospital admission. Based on our experience, we recommend the use of short-acting agents for general anaesthesia, and we advise against day case surgery in patients who require a general anaesthetic for longer than 60 min, or who need extensive surgery.