Background Melanoma and non- melanoma skin cancer show the highest increase of any form of cancer during the last 20 years.

Objective We wanted to know if we could find an increased rate of skin cancer precursors (actinic keratosis) in outdoor sportsmen.

Design Setting and Patients 900 patients with actinic keratosis (age 35–75) were investigated in their outdoor sport behaviour. Corresponding to the sport ( where, when, how long) we calculated the cumulative dose of sun with “UV Index hours”. The kind of tumor and tumor precursors were counted and the skin damage characterized with a confocal laser microscope. A healthy aged group was used for statistical analysis.

Results 27 different outdoor sports were found in our groups of patients. Watersport and skiing are known for a higher sun exposure, but only a few patients without statistical significance to the control collective were detected. But, in contrast, we found a 8.5 fold increased risk of skin cancer among golfers.

Conclusions We were able to give another hint for the relation of skin cancer development and the higher increase in outdoor sportsmen. From these data we developed in the UIPM for the athletes a "skin tumor prevention program". With this program the individual risk and the individual damage is analysed based on the cumulative UV-Dose of training and competition. Athletes, trainers and officials should be more sensitized in skin cancer prevention.