AbstractObjectives. According to the World Health Organization (WHO) the number of melanoma cases worldwide is increasing faster than any other cancer. In Europe the highest incidence rates have been reported in Scandinavia. The purpose of this study was to recognize possible risk factors for development of malignant melanoma, rank the risk factors according to their importance in the development of melanoma, and finally compare our results with the advice the Norwegian Cancer Society gives on this subject.Methods. A literature search was conducted using Medline and PubMed. We searched for literature published between January 1995 and June 2005 using the keywords “malignant melanoma”, “risk factors”, ”UVA”, ”UVB”, ”Genetics”, ”Immunosupression”, ”Naevus”. Results. Malignant melanoma has a multifactorial aetiology. The development of melanoma is the result of the interaction between different environmental, genetic and host factors. The major environmental aetiological factor is sunlight exposure, equated with UV radiation. There is controversy regarding the relationship between malignant melanoma and UVA and or UVB. Intermittent sun exposure and a history of moderate to severe sunburn in childhood are important risk factors. The presence of numerous naevi and atypical naevi are major host risk factors. Pigmentary characteristics, red-hair colour phenotype and fair skin are risk factors. Phenotypic risk factors are likely to be genetically determined. Two high-risk melanoma susceptibility genes have been identified, CDKN2A and CDK4. Smoking, stress, oral contraceptives and pregnancy are not involved in the carcinogenesis of malignant melanoma. There was a good correlation with the results from our literature search and the current advice from The Norwegian Cancer Society. Knowledge and understanding about the different risk factors and their interactions is important for developing prevention strategies.