Because the determinants of serum sex hormone levels in men have been infrequently studied, we investigated the relation of several personal characteristics to serum levels of testosterone (T), dihydrotestosterone (DHT), estrone (E1), estradiol (E2) and sex hormone-binding globulin (SHBG) among 98 Japanese American men in Hawaii, aged 52-74. The SHBG levels and T/(E1 + E2) ratios decreased progressively with increasing body mass index. The SHBG levels were also inversely associated with hematocrit levels. Serum androgen and estrogen levels did not correlate with smoking, alcohol intake, serum cholesterol, serum uric acid and blood pressure. Some of the associations observed in the present study may be implicated in the etiology of hormone-related neoplasms in men.