A 3-month-old male with kinky hair syndrome was given copper salts and purified ceruloplasmin, and the clinical and chemical responses measured. Initial plasma copper concentration was l5µ/100 ml and ceruloplasmin was undetectable. A seven-day course of oral cupric sulfate did not raise plasma copper or ceruloplasmin concentrations. After intravenous administration of cupric acetate on two occasions ceruloplasmin was detectable by chemical and immunological assays. Intravenous administration of purified human ceruloplasmin raised plasma ceruloplasmin levels acutely to normal. The in vivo half-life of this ceruloplasmin was within the range observed in infants with nutritional copper deficiency. These results support the contention of Danks et al. (Lancet, 1:1100, 1972) that intestinal copper absorption is defective in this syndrome. They further demonstrate that ceruloplasmin synthesis and decay appear normal when copper is available. The patient's clinical condition showed no change after copper and ceruloplasmin administration, suggesting that the neurological damage was irreversible. The possibility remains that earlier administration of copper or ceruloplasmin might be effective.