Irreversible damage of renal transplants may be prevented if insufficient graft perfusion can be detected perioperatively. Colour and spectral Doppler ultrasonography were performed in 30 consecutive renal transplants. The perfusion of the graft and the Resistive Index (RI) were evaluated perioperatively (perioperatively and less than 15 min postoperatively) and 24 h after the operation in all patients. In four cases (13.3%) RI > 0.9 was detected and immediate surgical correction of the cause led to a normalization (RI < 0.8) in all four cases. A RI < 0.9 required no intervention in 26 cases (86.7%). All renal grafts in this series were functioning 1 month postoperatively. In a comparative group, 30 consecutive transplants carried out at our institution without perioperative Doppler ultrasonography evaluation, a loss of four renal grafts perioperatively was recorded retrospectively. We conclude that perioperative ultrasonography Doppler evaluation may provide an easy applicable and reliable method for early detection of insufficient renal graft perfusion, allowing surgical correction before irreversible damage of the graft occurs. RI > 0.9 is pathological. A continuation of the study is required to clarify the long-term value of perioperative Doppler ultrasonography graft monitoring.