During a 40-day balance study, eight adult males were fed two levels of aluminium: 5 mg/day for 20 days (control diet) and 125 mg/day for 20 days (test diet). Every subject excreted more than 96% and more than 74% of his aluminium intake in his faeces when fed the test and control diets, respectively. Subjects excreted two- to five-fold more aluminium in their urine and had significantly higher levels of aluminium in their sera when fed the test diet rather than the control diet. No retention of aluminum was detected when faecal and urinary losses of aluminium were compared with intakes.