The Abductor Pollicis Longus (APL) is known to have a big variety in its number of insertion tendons. Because of that, studies about variations in its origin are not frequently achieved like studies about its insertion forms. This study describes an anatomic variation of the Abductor Pollicis Longus, with an anomalous venter originated of the inferior portion of the lateral border of the radio. Surgical and clinical implications are in relation principally with the big number of tendons of insertion of the APL, but there are related cases in the literature in that additional venter of this muscle also can be involved in the physiopathology of clinical syndromes, like the tenosynovitis of de Quervain.