The phrenic nerves of 80 cadavers were itwestigated. The presence of oneor more accessory phrenic nerves was found in 31 cases, of which 26 recordedthe appear once of such a nerves on one side only(12 left, 14 right)and 5 recor-ded its appearance on both sides. The percentage of such variation is 22.5%. The accessory phrenic nerves, as here investigated, may be originated from the5th cervical nerve (25.6%) or the 5th, 6th (33.3%) and less frequently from the3rd (18%) or the 4th, 5th (20.5%). Their relations to the main trunk are asfollows: 18.1% on the lateral side, 2.5% on the medial side and 1.9% on both sides.The accessory phrenic nerves, especially those at the lateral side, may reach thesize of the main trunk. The position where the accessory phrenic nerves join the main trunk showsmuch variation. It may occur above the first rib (15.3%), near the posterior orlower border of the subclavian vein (77.0%) or near the lateral side of the su-perior vena cava or the left anterior border of the aortic arch(7.7%).