Audit of unplanned hospital admission provides information to guide quality improvement measures and is a crude indicator of quality of care in ambulatory surgery. Our objectives were to re-audit factors relating to this outcome. Previous audit conducted in this unit revealed an unplanned admission rate of 3.7%. Data were collected between April 2000-March 2004. Of 13 592 day surgery patients, 238 (1.8%) unplanned admissions occurred. The admission rate displayed a falling trend and represented a significant improvement over the previous audit (p < 0.001). Unplanned admissions were most commonly caused by nausea/vomiting 23.5% (n = 56), postoperative bleeding 13.9% (n = 34), and unexpected extent/difficulty of procedure 11.8% (n = 28). Of all admissions, 18.5% (n = 44) were following orchidopexy, 16.4% (n = 39) following circumcision, and 12.6% (n = 30) following dental extraction. This audit shows that the unplanned admission rate is low and falling, and compares favourably with other units. Measures have been implemented targeting patients at high risk of admission.