An experimental study was designed to examine whether the blood supply of the muscle would be maintained by a reverse flow from the random pattern skin flap through the musculocutaneous perforators. A flap model containing rat rectus abdominis muscle and randomly based overlying abdominal skin was designed. Sixty rats were divided into four experimental groups as follows. In group I, scintigraphy and microangiography were performed in 10 and 6 rats, respectively, immediately after flap elevation. In group II, scintigraphy and micro anglography were performed in 10 and 6 rats, respectively, 2 days after flap elevation. In group III, surviving skin paddle area was evaluated in 16 rats 7 days after flap elevation. After evaluation of surviving skin paddle area, the same animals were used for microangiographic (n = 6) and scintigraphic (n = 10) studies at the same day. In group IV, histopathologic examination was done in six flap muscles each 2 and 6 weeks after flap elevation (n = 12). The mean percentage of surviving skin paddle area was 95.6 +/- 6.5% on postoperative day 7. Microangiography showed progressively developed blood flow from the skin to muscle through the musculocutaneous perforators in groups II and III, respectively. The radioisotope uptake of the operated muscle was 40.9 +/- 12.8% immediately after flap elevation (group I), 58.3 +/- 15.6% on postoperative day 2 (group II), and 70.7 +/- 25.6% on postoperative day 7 (group III). There was a significant difference only between group I and group III (p < 0.05, analysis of variance). Histopathologically prominent atrophy, lipomatoses, and fibroses were revealed at week 6. The poor circulation and viability outcomes of the muscle revealed in the study are because of immediately insufficient blood microcirculation at the distal part of the random pattern skin flap.