In the present study, the vascularization of flexor pollicis longus tendon of the thumb was investigated.As a result, the long flexor tendon was supplied by two major sources. Primarily by extrinsic blood vessels which were convarged to the tendon via vinculum longum and breve from its dorsal surface. Secondarily, by small intrinsic vessels which entered the tendon through the muscular tendinous end and coursed parallel to the collageneous bundles of the tendon.The vinculum longum was present in 38% of specimens observed whereas the vinculum breve existed in all cases.