A giant solitary trichoepithelioma measuring 8 cm in diameter and weighing 250 gm occurred on the thigh of a 58-year-old man. The lesion has been present for 20 years. To our knowledge, this is the largest trichoepithelioma reported to date. Histologic features included nests of basaloid cells with inadequate differentiation toward hair structures. The difficulties of differential diagnosis between this tumor and certain types of basal cell carcinomas are discussed; however, absence of epidermal ulceration, prominent stroma, epithelial lace-like tracts, minimal inflammation, and a 20-year-old history in our patient all point to a trichoepithelioma and not to a basal cell carcinoma.