Subject: Studies on functional flap angiogenesis demand an accurate technique for quantification of flap blood vessels. Technique: As an example, a 2.0 x 8.0 cm McFarlane flap is used in a rat model. After clinical evaluation, the left carotid artery in cannulated and 1µg prostvasine/100 g animal injected. 30 seconds later, 3 ml blood/100 g animal are withdrawn and the animal is euthanized. A mixture of liquid gelatine and bariumsulfate is slowly injected. 24 hours later, the fasciocutaneous tissue is surgically removed including the flap tissue. X-ray is performed on the specimen and the blood vessels are visualized. A computer program can be used to quantify the number of blood vessels/cm2 flap tissue. Practical value: This technique allows easy, reproducible and accurate quantification of small and new blood vessels. It may be usefull in studies to quantify angiogenesis in fasciocutaneous flaps for different purposes.