SYNOPSIS Two formulations of hexachlorophane have been compared for their antibacterial effects in respect of skin disinfection. It was found that the activity of hexachlorophane is dependent upon its vehicle of formulation. A 2-5% soap gel possesses broad-spectrum bactericidal activity with remarkable speed of kill, whereas a 3 % detergent formulation has no bactericidal action against Gram-negative bacteria and only a very slow action against Gram-positive bacteria.In practice the rapid action of the 2-5 % soap gel against both Gram-negative and Gram-positive transient skin bacteria can be achieved by correctly applying the preparation directly to the dry hands.It appears that the 2.5 % soap gel does not need to rely on mechanical removal of transient organisms as does the 3 % detergent.The 2-5 % soap gel is more dependable in its action on the resident bacteria than the 3 % detergent. It controlled the resident flora in the skin of all subjects tested whereas the latter appeared to be potentiated on the skin of certain individuals only.It has been possible to distinguish between the antibacterial effect on the resident organisms and the mere removal of transient bacteria by mechanical action of the 3 % detergent as opposed to antibacterial effect on residents and rapid antibacterial effect on transients by the 2-5o% soap gel.Many publications in Britain and the United States have described the value of hexachlorophane preparations as skin degerming agents. Various methods have been employed to determine the reduction of organisms, but not all distinguished between antibacterial action and mechanical removal due to the detergency of the preparation. Further, little work has been published on the reasons for using particular vehicles to carry the hexachlorophane. Hufnagel, Walter, and Howard (1948)