The authors make a survey of a series of a hundred Becker's nevi diagnosed in a recruiting center of the French National Service. It is a statistic study bearing on the male population, aged 17 to 26, in a French region which is supposed to be representative of the French male population of the same age. First of all the authors focus on the various clinical descriptions since this nevus was first described by Becker in 1949, then discuss the problems raised by pathogenic interpretation and the results of microscopic studies. About this lesion, usually said to be pigmentary and hairy, and generally appearing before 20 years of age, is still very little known. Then after a short explanation of their method of study the authors give original results. A hundred Becker's nevi were diagnosed among 19,302 young men, that is to say in a proportion of 0.52 p. 100. A study of the racial, genetic and pigmentary background doesn't enable to retain general causes but rather leads to think of local causes. Half of these Becker's nevi appeared before ten years of age, the other half appearing between 10 and 20. In only one quarter of the cases can the role of the sun be pointed out. The location of the nevi is variable; they are mainly situated on the trunk and only 32 p. 100 of them are located above nipples, which was believed to be the usual place of the lesion. Pigmentation in three quarter of the cases is light brown. The average surface is 125 cm2. Hairs can be seen in only a little more than half of the cases of no lesion associated to the nevus could be found. The study points out that Becker's nevi seem to be more various in their clinical expression and more pigment than could be thought through more classical description.