An analysis is presented which estimates the risk of progression of lentigo maligna (LM) to lentigo maligna melanoma (LMM) in U.S. whites using three data sources: the Health and Nutrition Examination Survey I for estimation of the age-specific prevalence of LM; the Surveillance, Epidemiology, and End Results Program for estimation of the age-specific incidence of melanoma; and the data from three melanoma registries for estimation of the age-specific case fraction of LMM among all invasive melanomas. The risk varies with age and is likely to be greater than estimated here for patients who present themselves for evaluation of changes in a lesion of LM. Our analysis suggests that the risk of progression from LM to LMM is substantially lower than is commonly believed.