There are widely differing accounts in the literature of the origin, course, and distribution of the nerves to the breast and especially to the nipple and areola. This, together with our own findings at operation, led us to investigate whether the accounts are inaccurate or the nerve supply is very variable or both. 15 breast specimens from dissecting room cadavers, 12 female and 3 male, were dissected to study the nerve supply of the breast in detail. In the female, the breast received its innervation from the lateral and anterior cutaneous branches of the second to the sixth intercostal nerves and from the supraclavicular nerves. On the lateral side in the 12 females, branches from the third (9/12), fourth (12/12) and fifth (4/12), and on the medial side branches from the second (3/12), the third (6/12), the fourth (4/12) and the fifth (2/12) intercostal nerves were traced to a plexus under the areola. Branches from the sixth intercostal nerve supplied the lower part of the breast but there was no direct branch to the nipple. The nerves to the nipple lay in the superficial fascia and passed through the subdermal tissue of the areola to form a plexus under it. The extent of the contribution by each nerve was variable, and it differed even on the left and right of the same cadaver. The nerve often described as passing through the inferolateral part of the breast to reach the nipple is a deep branch from the anterior division of the fourth lateral cutaneous nerve. This was present in 11/12 of the female breasts but it is not the only nerve to reach the plexus under the areola as sometimes claimed. The male breast had a similar nerve supply but the nerves were lying close together, whereas in a female breast they are spread out more widely.