It has been suggested that increased risk for testicular cancer occurring worldwide may be due to exposures during fetal development. Lifestyle or environmental exposures may be the most important predictors of risk. However, few studies have directly examined these exposures prospectively. The Child Health and Development Studies is a 40-year follow-up of 20,530 pregnancies occurring between 1959 and 1967. There were 20 cases of testicular cancer diagnosed through 2003 among sons with a maternal interview in early pregnancy. Cases were matched to three controls on birth year and race. Odds ratios and 95% confidence intervals were calculated with exact conditional logistic regression. Compared to controls, mothers of testicular cancer cases were more likely to drink alcohol (unadjusted odds ratio, 3.2; 95% confidence interval, 0.83-15.48 for above vs. below the median for controls) and less likely to drink coffee (unadjusted odds ratio, 0.19; 95% confidence interval, 0.02-1.02 for above vs. below the median). Case mothers were neither more nor less likely to smoke. Although low power may limit interpretation of negative results, the prospective design minimizes bias. In this cohort, maternal serum testosterone in pregnancy was previously reported to be lower in women who drank alcohol. Because populations with high testicular cancer risk also have lower maternal testosterone, we suggest that testosterone could play a role in explaining the higher risk of son's testicular cancer among mothers who drank alcohol during pregnancy.