The significance of obesity as a risk factor for postoperative complications was determined in a consecutive series of 229 cases of revision total hip replacement. The body mass index (BMI) was used as an objective measure to classify the patients. The group-wise analysis of data included all medical and procedure-related complications, the number of fatal cases, operative time, requirement for analgesics, the number of transfusions and perioperative haemoglobin levels. The results of our study demonstrate a clear association between obesity and operative time, whereas no statistically significant relationships were observed between obesity and the other parameters. We conclude that obesity does not have any significant influence on perioperative morbidity and mortality but is clearly related to operation time and, therefore, to higher costs per operation.