• Microscopically controlled excision of melanoma by the chemosurgical method ensures complete eradication of any unsuspected outgrowths from the clinically observed tumor mass. The method differs from the chemosurgical techniques used for excision of cutaneous carcinomas in the following two respects: the tissues always are chemically fixed in situ before any incisions are made in order to minimize the chance of dissemination, and an extra margin of tissues is removed after reaching a microscopically melanoma-free plane in order to encompass possible outlying melanomatous satellites in the peritumoral lymphatics. In a series of 103 consecutive cases of melanomas of the nodular, superficial spreading, and lentigo maligna types, there were 86 determinate cases with a five-year cure rate of 50%. This is a high rate for a series in which 69% were nodular melanomas and 64% invaded to subcutaneous tissues (Clark's level 5). (Arch Dermatol 113:285-291, 1977)