A large series of 211 Spitz nevi is reviewed. 30% of the lesions were from patients 20 years of age and over. The trunk and lower extremity were most commonly involved. There were no significant histologic differences between cases from adults and children. Features which may help in differentiating atypical Spitz nevi from malignant melanoma include the presence of some nevus cell maturity at the base, an absence of atypical mitoses, no significant upward epidermal spread and the nuclear chromatin pattern. Cancer 40:217–225, 1977.