The delay technique is an established method of enhancing flap survival. This investigation attempts to determine which of two delay techniques results in the best delay effect by measuring their relative abilities to capture adjacent vascular territories in a rat model. A dorsal flap based on the iliac branch of the iliolumbar artery with a captured random zone corresponding to the axial territory of the lateral thoracic artery was used in the evaluation. Sprague-Dawley rats (350-400 g) were randomly assigned into three groups. Group I was the control group. In group II, the circumferential borders of the animal's dorsum were incised without undermining and the dominant pedicle of the lateral thoracic flap was divided. In group III, the medial and lateral borders of the flap were incised and undermined as a bipedicled flap, violating the musculocutaneous perforators. The dominant pedicle of the lateral thoracic artery was also divided. Group III had the greatest survival with only 9% of flap area necrosis compared to 28% and 21% for groups I and II, respectively. These differences were statistically significant. The results suggest that musculocutaneous perforators provide a substantial vascular source to the tissue at risk and should be considered in selecting a delay technique.