Ovarian hyperstimulation syndrome (OHSS) is a potentially fatal condition associated with the therapeutic induction of ovulation in infertility. Liver function abnormality has been previously reported in four patients, one of whom had ultrastructural abnormalities on liver biopsy. This paper describes a patient presenting with severe OHSS 16 days after ovulation had been induced. Liver function abnormality was apparent 11 days later, with a sustained rise in alkaline phosphatase and aspartate aminotransferase (AST) which lasted up to 2 months. A liver biopsy performed during the second month of her protracted hospital admission showed marked zonal fatty change (acinar zone 1) and associated inflammation, with mitochondrial crystalline inclusions and rough endoplasmic reticulum dilatation on electron microscopy. This report discusses the clinical features and possible aetiological factors.