Background : The differentiation of syphilids from other skin decreases is frequently difficult due to considerable variations of clinical and histologic pattern. The most common histologic changes in secondary syphilis are swelling & proliferation of endothelial cells and the presence of a perivascular infiltrate containing plasmia cells. But often, these findings are absert or inconspicuous. Objectlve : We examined the histopathologic findings of secondary syphilis in relation to the clinical types of the skin lesion. Methods : 36 biopsy specimens from twenty-nine serologically and clinically confirmed cases of secondary syphilis (15 macules, 8 papules, 2 condylomata latas and 11 papulosquamous lesions) were examined. Raeults : The histopath,ologic findings of secondary syphilis showed comparative differences according to the clinical types of the skin lesion. The plasms cell infltrates were absent or sparse in 14 csses(39%) and the plasma cell infiltration was significantly correhted with the age of skin lesions(p=0.02197). Vascular changes were seen in 32 cases (89%), but the incidence of endothelial proliferation was less(25%). Conclvsion : This study demonstrates the histopathologic findirigs of secondary syphilis in accordance to the clinical morphology of the eruption and thus, help to differentiate syphilids from other skin diseases. (Kor J Dermatol 1993; 31(2): 197-203)