Diphtheritic skin lesions are known to be relatively common in tropical as opposed to temperate climates, but the possible presence of Corynebacterium diphtheriae in skin lesions has not been investigated in East Africa, where classical diphtheria cases are rare. The authors therefore studied septic skin lesions and skin ulcers in 139 preschool children and schoolchildren in Uganda. A high percentage (up to 60%) of C. diphtheriae lesions was found, a majority of the isolations being of the mitis type. At the same time, low respiratory carrier rates for C. diphtheriae were found. The practical importance of the skin reservoir of C. diphtheriae for the development of specific diphtheria immunity in the tropics is stressed.