The aim of this study was to quantify the incidence of complications following inguinal herniotomy in small babies weighing 5 kg or less. This was a retrospective review of inguinal herniotomies performed in our unit between December 1997 and March 2002 on babies weighing 5 kg or less. A total of 154 patients underwent hernia repair, of which 125 patients (221 hernias) were available for review (81%). The median weight at surgery was 3.6 kg (range 1.7-5 kg) and 84 patients (67%) were classified as premature (< 36 weeks gestation). Thirty-three patients presented with an irreducible hernia, in whom all but one were successfully reduced prior to surgery. Patients were reassessed at a clinic following surgery and follow-up data was obtained from the clinic notes after a median follow-up of 3 months (range 1-60 months). Five cases of hernia recurrence occurred in four patients (2.3%) and the incidence of testicular atrophy was 2.7% (six patients). In the testicular atrophy group, four of the six patients presented with an incarcerated hernia and of these, three were noted to have evidence of ischaemia at operation. There were six cases of high testes requiring subsequent orchidopexy (2.7%). Although neonatal inguinal herniotomy is a technically demanding procedure, this series has demonstrated a low complication rate. Testicular atrophy was associated with a history of preoperative incarceration in the majority of cases.