SUMMARYThe effects of a commercial trichlorocarbanilide-containing deodorant soap and a commercial plain soap upon the cutaneous flora of individuals were compared. Using a cross-over design, 21 volunteers (10 women and 11 men) washed their forearms at least once a day with one soap for 3 weeks and then switched soaps for another 4 weeks use. By analysis of variance no significant difference in total colony counts was noted among individuals in their use of the two soaps. With the exception of individual variation, neither sequence of use, sex, nor any combination was influential. However, in 20 of 21 subjects an alteration in the composition of skin flora was observed. The deodorant soap, which in six cases increased total flora, tended to reduce or eliminate diphtheroids in 12 of 17 carriers (71 %). Fewer kinds of bacteria were also noted. More Staphylococciss epidermidis was seen with the plain soap, but washing with the deodorant soap seemed to favour Acinetobacter calcoaceticus and Micrococcus luteu8. The impact of this alteration and the use of total counts to measure effectiveness ofdeodorant soaps were brought into question.