The use of rhodotorulic acid (RA) as an iron-chelating drug was suggested by experiments in hypertransfused rats in which urinary and fecal iron excretion were significantly enhanced in response to RA. The toxicity of the drug appears to be minimal at a parenteral dose less than 250 mg/kg. An increased excretion of zinc was the only notable side effect of the drug at the doses used. When administered i.v. to humans, RA was only 16% more effective than desferrioxamine (DF). Pharmacokinetic studies showed that RA persisted in the bloodstream of dogs 6 times longer than desferrioxamine after an intravenous injection. Accordingly RA was evaluated as a potential repository drug. While animal experiments were encouraging, human subjects experienced a painful local reaction to RA administered either i.m. or s.c. as a suspension in physiological saline. Accordingly it appears that RA is best looked at as a second line drug, unless a means can be found to obviate local inflammatory reactions.