The aim of this study was to assess the effect of allopurinol on rat groin flaps rendered ischaemic by selectively occluding the feeding femoral artery and reperfused by means of microsurgical anastomosis. For the establishment of the critical arterial ischaemia time, the femoral artery of 29 rat groin flaps isolated on the inferior epigastric pedicle was occluded for 10, 12 and 14 h. Following 12 h or more of ischaemia, 5.25% of the flaps survived, compared to 40% survival after 10 h (p = 0.04). In the second stage of the study, 34 rat groin flaps were subjected to arterial ischaemia for 12 h. Of these, 12 rats received allopurinol solution I.V. 30 min prior to reperfusion, 10 received the vehicle solution (control) and 12 underwent no treatment (control). After 7 days, survival of the groin flaps was observed in 41.7%, 0 and 8.3% of the groups, respectively (p = 0.0164). This study suggests that systemic administration of allopurinol has a beneficial effect on rat arterial ischaemic groin flaps and may prolong their critical ischaemia time.