BACKGROUND Malignant degeneration of chronic ulcers such as nonhealed burn wounds has been described in the literature, but this phenomenon has never been quantified in an epidemiologic study. We investigated the risks for skin and other cancers among patients with a prior burn. METHODS We identified 16,903 patients from the Danish Hospital Discharge Register who had been admitted to a hospital with a thermal or chemical burn during 1978 to 1993. The cohort was followed for cancer in the Danish Cancer Registry through 2002, and the cancer incidence in the cohort was compared with that in the general population of Denmark. RESULTS Patients with burn had 139 skin cancers, with 189 expected, yielding a standardized incidence ratio of 0.7 (95% confidence interval = 0.6-0.9). This reduced risk was due mainly to deficits of basal cell carcinoma and malignant melanoma, whereas the number of squamous cell carcinomas observed was close to expected. We saw no consistent increases in risk for skin cancer in the subgroups of patients with the most severe injuries or with the longest periods of follow up. CONCLUSIONS The tendency to malignant degeneration of burn scars, described in previous reports of case series, did not result in an excess of squamous cell carcinoma of the skin or of any other type of skin cancer during up to 25 years' follow up of a large unselected cohort of patients hospitalized for burn injuries.