Human blood selenium (Se) levels have been related to the types of food consumed, bioavailability of Se, and various disease states, including cancer. Some of these interrelationships were investigated in this study in Corvallis, OR (a low soil-Se region) using adult vegetarian and omnivorous subjects, some of whom had hormone-dependent cancer. The study groups were comprised of 48 Seventh-day Adventist vegetarians, 16 Seventh-day Adventist nonvegetarians, 52 non-Seventh-day Adventist nonvegetarians, and 16 nonvegetarian hormone-dependent cancer subjects. Fasting blood samples and 3-days dietary intake information were obtained from each subject. Whole blood Se levels, measured fluorimetrically, correlated positively with dietary protein, riboflavin, niacin, and oleic and linoleic acids but not with 11 other nutrients. Due to limited literature values, dietary Se could not be assessed. There was no significant difference in blood Se values between the four groups (which ranged from 0.069 microgram Se/ml for Seventh-day Adventist nonvegetariants to 0.112 +/- 0.050 microgram Se/ml for non-Seventh-day Adventists nonvegetarians and nonvegetarian hormone-dependent cancer patients). All values were well below averages reported for other regions of the United States. These data suggest a relationship between blood Se and the consumption of meat, milk, and cereal products, but it is not simply a difference between the vegetarian and nonvegetarian diets.