Nutritional status of manganese in 10 adult males was monitored through a 47-d period by measuring manganese in serum and urine and by chemically analyzing duplicate portions of all foods and beverages consumed on 3 d, with computer analysis of dietary records for 10 additional days. Subjects consumed 0.52-5.33 mg Mn/d; 50% of the time they consumed less than the 1980 Estimated Safe and Adequate Daily Dietary Intake for manganese. Subjects on average (+/- SEM) excreted 7.0 +/- 0.5 nmol Mn/g creatinine; their average serum manganese concentration was 19.3 +/- 1 nmol/L. These potential indices of manganese exposure were not correlated with the subjects' dietary intakes of manganese or other minerals. However, serum manganese concentrations tended to be elevated (p less than 0.064) in five subjects who consumed 15 mg chelated Mn/d for 7 d.