To assess the clinical characteristics of valproate (VPA)-associated pancreatitis, information from three sources was gathered: (a) a survey among 507 physicians with a special interest in treatment of epilepsy, (b) a review of the authors' patient population, and (c) a review of the literature. Of 366 physicians answering the survey, 53 (14.5%) reported a case of pancreatitis. Thirty-nine cases were available for review (24 from the medical literature, 12 from the survey, and 3 from the authors). Pancreatitis appeared to be more frequent in young persons (mean age 16.4 years) but may occur at any age. The highest risk appears to exist during the first months of treatment: 43.8% of the cases developed during the first 3 months, and 68.8% developed during the first year. Seventy-six percent of patients were receiving polytherapy, and 41% had some form of associated chronic encephalopathy. In most patients, the reaction was rapidly reversible when VPA was discontinued. It was severe in 6 patients, with 3 deaths reported. Rechallenge with VPA was attempted in 9 patients, with a high incidence of relapses. Asymptomatic elevation of serum amylase in patients receiving VPA was reported by 40 (10.9%) of the physicians surveyed. Awareness of the problem and early discontinuation of VPA may be effective in preventing serious reactions.