Partial flap loss is a common complication of the distally based sural fasciocutaneous flap. We present a modified technique of a sloped skin island design to improve the reliability of the flap when used to reconstruct a longitudinal distal pretibial defect or transverse heel and ankle defect. Thirty-one flaps with the slope-designed skin island were used to reconstruct such defects in 30 patients. In the modified technique, the skin island was rotated toward the vascular axis of the flap. The defects were located in the distal pretibial region in 7 cases and the ankle and heel region in 24. The horizontal dimension of the skin island decreased by an average of 5.6 (range 2.5 to 14.8) cm with the sloped design, and the rotation angle varied from 42° to 90° (mean 69°). Of the 31 flaps, 29 survived, 1 developed marginal necrosis, and 1 developed lateral partial necrosis. The sloped design of the skin island is applicable to reconstruction of longitudinal distal pretibial or transverse heel and ankle defects. The modified technique can decrease the horizontal dimension and increase perfusion of the skin island, thus improving the reliability of the flap.