An 18-year-old woman developed an acute haemolytic anaemia, acute transient renal failure and progressive hepatic failure. Coeruloplasmin and serum copper concentration were normal; a Kayser-Fleischer ring and any neurological symptoms were absent initially. Liver biopsy was contraindicated because of increased bleeding tendency. Wilson's disease was diagnosed only after the acute renal failure had regressed, on the basis of the urinary copper excretion (2890 micrograms/d, rising to 7330 micrograms/d after D-penicillamine administration). Progressive liver failure required transplantation. After it the patient quickly recovered and is now, two years later, free of disease. -This case demonstrates that Wilson's disease may be difficult to diagnose at the time of initial acute manifestation. But it can be recognized early from the pathognomonic low alkaline phosphatase and by calculation of free serum copper.