The use of an external oblique muscle-cutaneous flap in the reconstruction of large chest wall defects after mastectomy is described. The flap is drown as a V-Y advancement-rotation flap, laterally based, on the ipsilateral abdominal wall. The flap extends from the posterior axillary line to the linea alba, vascular supply is provided by the musculo-cutaneous perforating arteries of the intercostal vessels. Mobilization starts medially including the anterior rectus sheath, décollement continues between the external and the internal oblique muscles as far as the posterior axillary line. The abdominal wall, after flap mobilization, is reinforced by the plication of the internal oblique sheath. The flap was used in 13 patients with major anterior chest-wall defects after mastectomy. In one patient a marginal skin necrosis of about 2 cm was observed. The flap described differs from other external oblique flaps already described in several technical innovations that allow to obtain better functional and esthetic results.