Arterialised venous flaps provide skin with thin subcutaneous tissue, making them suitable for covering skin defects on the hand. However, they are often susceptible to subsequent unpredictable superficial or partial necrosis. We performed a retrospective analysis of the free arterialised venous flaps that we had used in patients to identify prognostic factors that correlate with flap necrosis. 51 flaps in 51 patients met the following criteria and were subjected to statistical analysis. They had an elliptical shape and were harvested from the medial aspect of the ipsilateral forearm to cover skin deficits distal to the wrist joint. Each flap contained one axial flow-through subcutaneous vein, the vein stumps of which were approximated to a recipient artery and a recipient vein. The patient's age at the time of surgery, the recipient site of the flap and the size of the flap were examined in each case. Multivariate analysis showed that the size of the flap was the factor that correlated statistically with a successful result after a flap operation. Arterialised venous flaps in which the product of the lengths of the long and short axes (mm) was less than 767 were less likely to develop necrosis of the skin.