The increasing frequency of malignant melanoma (MM) is believed mainly to be due to the habit of sunbathing, which has an impact on the skin due to ultraviolet radiation, especially if intermittent and causing sunburn. Frequent use of tanning booths possibly increases the risk of MM but the question has not been settled. Use of sunscreens has a certain prophylactic effect on actinic keratoses, but no documented effect on MM. This does not imply that sunscreens are not advisable, but stresses the importance of correct use of sunscreens together with other sun protective measures. Primary prevention of MM is mainly a question of minimizing the impact of ultraviolet radiation (including tanning booths) on the skin: limit time in the sun, cover up with clothing, and use a sunscreen with a protection factor of at least 15.