Recurrence of gastro-oesophageal reflux (GOR) following redo Nissen fundoplication represents a significant clinical problem. The aim of this study was to identify factors predicting failure of redo Nissen fundoplication. The notes of children who underwent redo Nissen fundoplication for recurrent GOR in a single institution between June 1994 and May 2005 were reviewed. Data are reported as median (range), or as numbers of cases. Multiple logistic regression analysis, using type of first fundoplication, neurological status, presence of gastrostomy, age-weight, retching-gas bloat after first fundoplication, associated anomalies, oesophageal atresia and length of follow-up as factors, was used to generate a model to identify factors predicting recurrent vomiting (failure) after redo. Eighty-one children underwent redo Nissen fundoplication 15.9 months (0.2-176) after the initial Nissen fundoplication. In 29, the first Nissen was laparoscopic. Age at redo Nissen fundoplication was 3.3 years (0.3-15.9) and weight 12.8 kg (5-60). Thirty-four children (42%) presented with recurrent vomiting (failure). Overall, the model successfully predicted vomiting (failure) after redo fundoplication (P = 0.009). Open surgery at first fundoplication (P = 0.011) and neurological impairment (P = 0.046) were both significant predictors of redo failure in the model, whereas presence of gastrostomy (P = 0.035) and older-heavier age-weight (P = 0.028) were associated with significantly better results. Retching-gas bloat, associated anomalies and oesophageal atresia were not significant predictors of failure. Redo Nissen fundoplication has a high failure rate. Risk factors are open fundoplication at first operation and neurological impairment. Redo fundoplication after primary laparoscopic Nissen has a lower risk of failure.