We reviewed retrospectively a cohort of 80 patients with hyperemesis gravidarum hospitalized between 1976 and 1986 for the presence of abnormal liver enzymes and ketonuria. Thirteen (16%) had abnormal liver enzymes, generally less than four times the upper limit of normal. In this group, hyperemesis gravidarum began at the 14th week of pregnancy as compared to the 6th week in the normal enzyme group (p less than 0.01). Both groups were similar with regard to age, number of children and pregnancies, and duration of vomiting. Ketonuria was significantly more severe (p less than 0.01) in the abnormal enzyme group, implying a more severe state of starvation and dehydration. The correlation coefficient between the degree of ketonuria and level of liver enzymes was low for alkaline phosphatase (r = 0.18), GPT (r = 0.15), and GOT (r = 0.28). The concept that dehydration and starvation are important factors for the induction of liver cell injury is supported by our data. Lack of correlation between the degree of ketonuria and liver enzyme levels is suggestive of other mechanisms (hormonal, genetic) that may interact to produce transaminasemia.