Few studies have calculated the incidence of second primary melanoma. Previous studies were mainly based on relatively small hospital-based cohorts. This study describes the incidence of second primary melanoma in a large cohort identified using population-based cancer registry data obtained from the SEER program of the National Cancer Institution in the USA for the period 1973 to 2002. The incidence of second primary melanoma was estimated in males and females by age, anatomic site, histology and stage of the first melanoma. Poisson regression model was used to adjust relative rates for other factors.