Insertion of ventilation tubes is regarded as a simple, effective and safe treatment for recurrent otitis media or prolonged middle-ear effusions. We conducted a prospective observational study of 112 children to ascertain what early post-operative complications were experienced. Our findings were consistent with previously published figures for post-surgical otorrhoea and obstruction rates, at 13.5 per cent and 4 per cent (by ear), respectively, using intra-operative administration of antibiotic/steroid ear drops. We identified unique characteristics of differing ethnic groups with regard to findings at surgery and post-operative outcomes. There was a tendency for grommets placed in the left ear to be extruded early and Maori andPacific Islanders were significantly more likely to have a non-functioning tube (blocked or extruded) in the early post-operative period. Overall, one in four children developed a post-operative complication (otorrhoea or non-functioning tube) suggesting that early and close follow up may allow timely identification and intervention where required.