Recent figures on admissions to treatment facilities in Vietnam indicate how greatly skin diseases hamper military operations. In 1966 and 1967, dermatoses were the third highest cause for admissions because of disease. In 1968 they dropped to the fourth highest cause. These figures fall far short of showing the full impact. They do not include the dermatologic patients treated ambulatorily which are double the number treated for any other condition. Nor do the overall figures show the incidence in combat troops where it is many times higher than in support elements. Among troops operating in wet terrain such as the Mekong Delta, skin diseases can account for as high as 70% of all man-days lost. The causes for the reduced incidence in 1968 are not known.