The aim of the present study was to evaluate the frequency with which histologically confirmed dysplastic nevi are observed among patients with superficial spreading melanoma compared to patients with nodular melanoma. A pathology review of 117 new cases of first primary nonfamilial cutaneous melanoma identified 61 patients with superficial spreading melanoma and 19 with nodular melanoma. Study participants received a physician-conducted skin examination which included enumeration of clinically benign and atypical nevi and the surgical excision of the clinically most atypical nevus. Patients' dysplastic nevus status was established by histological review of the clinically most atypical nevus. A comparison based on the tumor subtypes showed that dysplastic nevi occur nearly four times more frequently among patients with a prior diagnosis of superficial spreading melanoma relative to nodular melanoma (odds ratio = 3.6; P = 0.03).