In a retrospective single-centre study 170 consecutive patients were included who received a Kotz modular prosthesis after resection of bone tumours of the proximal femur to evaluate the management of prosthetic infection. Infection occurred in 12 of 166 patients available for follow-up (six males; six females; mean age, 47 years; range, ten to 75 years) after a mean of 39 months (range, one to 166 months; infection rate, 7.2%). Mean follow-up was 54 months (range, four to 200 months). One patient died of septic shock. Two patients were treated by wound revision only. Treatment of infection in the remaining patients was one-stage revision in eight and hip disarticulation in one. Infection control by one-stage revision was achieved in five of eight patients; re-infection occurred in three patients and was successfully treated by further revision in all of them. The overall success rate for controlling infection was 83.3%.