Using data from the Health Professionals Follow-Up Study, we prospectively examined the relationships between height, body mass index, waist and hip circumferences, and risk of total and advanced (extraprostatic and metastatic) prostate cancer. In addition, we assessed adiposity during childhood, adolescence, and early, middle, and late adulthood using pictograms in relation to prostate cancer risk. Between 1986 and 1994, 1,369 cases of prostate cancer (excluding stage A1) were confirmed in 47,781 men. Adult body mass index and waist and hip circumferences were not appreciably related to risk of total prostate cancer or advanced prostate cancer. In contrast, preadult (age 10) obesity assessed in 33,336 men in 1988 was prospectively related to lower risk of advanced [relative risk (RR) = 0.72 with 95% confidence interval (CI) = 0.47-1.10, between high and low quintiles; P(trend) = 0.06] and metastatic prostate cancer (RR = 0.38 with 95% CI = 0.19-0.77; P(trend) = 0.004). For the advanced lesions, an association was observed with height (RR = 1.68 with 95% CI = 1.16-2.43 for men 74 inches or taller, relative to men 68 inches or shorter; P(trend) = 0.01). In an analysis limited to particularly aggressive forms of prostate cancer, i.e., cases found to be metastatic at time of diagnosis between 1988 and 1994 after a negative digital rectal examination in 1988, we found that obesity at ages 5 and 10 had a strong inverse association (RR = 0.16 with 95% CI = 0.05-0.54, between high and low quintiles at age 10) and that tallness had a strong direct association with risk of metastatic disease (RR = 2.29 with 95% CI = 1.04-5.05, for height > or = 74 inches versus < or = 68 inches). Our findings suggest that the preadult hormonal milieu, as reflected in attained height and childhood obesity, may have a strong influence on prostate carcinogenesis.