Patients with single primary melanomas have an increased risk of developing subsequent melanomas. Secondary tumors diagnosed within and after 3 months are termed "synchronous" and "asynchronous," respectively. To compare tumor distributions and survival characteristics between patients with second primary melanomas and those with single primary melanomas. Retrospective cohort study. Data were collected from an institutional database from 14,029 patients with a diagnosis of a primary melanoma seen between 1970 and 2004. The synchronous and asynchronous cohorts demonstrated significantly improved survival probabilities compared with the single primary cohort (P = .04 and .002, respectively). Single primary lesions (2.2 ± 2.3 mm) were significantly thicker than the first-identified synchronous (2.0 ± 1.7 mm) and asynchronous (1.7 ± 1.3 mm) lesions. Synchronous lesions were more likely to be anatomically concordant compared with asynchronous lesions (55.7% vs 38.2%, P < .001). Single-center study design and incomplete records for second primary melanoma Breslow depth and histopathology. Patients with second primary melanomas demonstrated a significant survival advantage and thinner lesions compared with those with single primary melanomas. Our reported tumor distributions support the role of full body skin examinations, with attention to the region of initial diagnosis.