We conducted a prospective study of diet in relation to the incidence of basal cell carcinoma of the skin in a cohort of 73,366 women who were 34 to 59 years old in 1980 and without previous skin or other cancer. During 4 years of follow-up, 771 incident cases of basal cell carcinoma were diagnosed. When adjusted for other risk factors, women in the highest quintile of energy intake were at higher risk of basal cell carcinoma compared with those in the lowest quintile (relative risk, 1.28; 95% confidence interval, 1.02 to 1.60). No significant associations were observed between risk of basal cell carcinoma and energy-adjusted intake of dietary fat, carotenoids with vitamin A activity, and retinol, vitamin C, vitamin D, and vitamin E, either with or without supplements. Use of specific vitamin A, C, D, or E supplements, or multivitamins, did not materially alter risk. Although the period of follow-up was relatively short, these data are most consistent with no major role for these nutrients in the etiology of basal cell carcinoma.