Data concerning risk factors for the development of cutaneous malignant melanoma (MM) were abstracted from published case-control studies. Relative risks (more appropriately "odds ratios") and 95% confidence intervals were quoted or calculated for each risk factor in each study. Those risk factors that were reported to be significant in over half of the studies include: phenotypic factors (blue eyes, blond or red hair, light complexion, freckles, sun sensitivity, and inability to tan); personal history of non-melanoma cutaneous cancer or precancer; higher socioeconomic status; increased numbers of nevocytic nevi; and bursts of sun exposure. Further study is needed on family history and personal history of MM; these were not found to be significant risk factors in over half the reviewed case-control studies. This review leaves out other undoubtedly important risk factors such as dysplastic nervus syndrome and race, which need investigation by the case-control method. Determination of risk factors allows the identification of that subset of the population most at risk for the development of MM. Given the continued increase in the incidence of MM, these data can help to focus preventive measures on the more susceptible subgroups of the population.