The lateral thigh fasciocutaneous flap described by Maruyama et al in 1984 is a useful method for the repair of ischial and trochanteric defects. We clinically re-evaluated the potential vascular territory of the nutrient artery for this flap, i.e., the first profunda perforator, and have newly designed the postero-lateral thigh V-Y flap in the area including the proximal two-thirds of the posterior thigh. This flap was applied to five difficult or recurrent ischial defects, and satisfactory results were obtained in all cases. For the reconstruction of ischial defects, the postero-lateral thigh V-Y flap has the following advantages; the proximal and well-vascularised portion of the flap is inserted into the area of the previously excised pressure sore, and this flap can potentially be readvanced if a recurrent pressure sore should develop. A Z-plasty can be performed to prevent excessive tension on the skin closure at the junction of the V-Y advancement flap. The postero-lateral thigh V-Y flap can be considered one of the first-line options for both primary and recurrent ischial pressure sores.