1. Six healthy male volunteers received intravenous injections of 26Al as citrate. Accelerator mass spectrometry and gamma-ray spectrometry were used to determine levels of the tracer in blood and excreta at times up to 5-6 d. 2. There was a rapid clearance from blood (mean 2% of injection remaining after 1 d) and major loss in urine (59% up to 1 d), but 27 +/- 7 (s.d.)% was retained in the body at 5 d. Faecal excretion was negligible (1% up to 5 d). 3. The mean results accord with the early metabolic pattern in the single subject of a previous, more extensive study, who had retained 4% of the injection after 3 y. Together, the two studies point to the likelihood of large inter-subject differences in the long-term accumulation of dietary aluminium by populations receiving a given level of daily intake.