Free tissue transplantation is a routine procedure in reconstructive surgery. Although a lot of free flap techniques have been described, the postoperative management of complications has gained only little interest. Nevertheless, complications of perfusion after free tissue transplantation are not rare and require a systematic approach. The aim of this study is to classify perfusion failures with a simple grading system prospectively on a large clinical series and to evaluate the results of treatment to improve management. In the past ten months, 70 consecutive free flaps have been performed. By the end of the operation, the operating surgeon gave a prognosis concerning the probability of a possible perfusion complication. Postoperative monitoring was done exclusively by clinical examination (colour, time for recapillarisation and bleeding after puncture). According to these parameters, arterial and venous insufficiencies have been classified into four grades. After recording type, time and treatment of a postoperative complication, the result of treatment was rated subjectively and a cause was noted when possible. The final result was classified either as total flap loss, partial flap loss or successful tissue transplantation. A total of 28 (40%) complications, which were treated with an average of 2.1 options, were recorded. The ratio between arterial and venous failure was 15:13. In 21 cases surgical intervention became necessary (intraoperative n = 12, postoperative n = 9). The arising complication was diagnosed correctly in nine cases by the operating surgeon. In ten cases, the cause of the complication remained unclear. In 18 cases, the complication was treated successfully without any flap loss. In six cases partial flap loss was observed and in four cases a total flap loss had to be accepted. Our results confirm that only few objective criteria for treatment options with perfusion failures after free tissue transplantation exist. Nevertheless, the presented classification is a useful tool for standardized evaluation of the results. The various salvage techniques result in positive outcomes for most of the patients.