In the search for possible causes for the enormous increase in testicular cancer incidence in Denmark, we tested the hypothesis that a high fat or calorie intake in adolescence and consequently relative obesity is a promotional factor for testicular cancer. A total of 438 cases and three controls for each case were included in the study. Data originated from health examination of men liable for military service. Data were analysed by logistic regression analysis. No systematic statistically significant differences in body measurements [height, weight and body-mass index (weight/height2)] could be shown. Rather than being obese a slight trend was observed towards the future victims of testicular cancer being lighter, smaller and thinner than unaffected controls.