This study was designed to investigate the anatomy of the internal mammary (thoracic) artery (IMA) and comitant vein(s) (IMV) relevant to their use in microsurgery. We dissected the internal mammary (thoracic) vessels bilaterally in 86 cadavers from the clavicle down to the 6th rib. At the level of the 4th rib, the distance between the sternum and the IMA was large enough [range 10.0-23.6 mm] and the diameter of the IMA [range 0.99-2.55 mm] and comitant vein(s) [range 0.64-4.45 mm] wide enough for both end-to-end and/or end-to-side anastomosis. These results were in close agreement with supplementary measurements obtained by Doppler ultrasound in 34 healthy female volunteers. Based on all these findings we suggest that the internal mammary vessels are suitable recipient vessels for free tissue transfers in the thoracic region, especially for breast reconstruction with the free transverse rectus abdominis myocutaneous (TRAM) flap.