Of 127 patients with primary neoplasms of the scrotal wall 10 had a solitary leiomyoma arising from the tunica dartos. These benign asymptomatic lesions occur in middle age white men and are often incorrectly diagnosed. Simple surgical excision is curative. The 11th case is described because of the malignant course which followed irradiation of the benign tumor. A cell arising from single smooth muscle cells within the corium is proposed as the cell of origin.