To show a possible correlation between drug-induced hyperprolactinemia and improvement of hysterical neurosis of the conversion type, we followed 18 patients monitoring clinical somatic and psychic symptoms as well as serum prolactin levels. Six patients were treated with haloperidol and 12 with sulpiride; after 2 months sulpiride was administered at half the daily dose to 6 patients previously treated with the same drug. Clinical evaluation showed that sulpiride treatment led to a greater improvement compared to the haloperidol group. The different effectiveness of treatment could be explained by the different hyperprolactinemic potency. The therapeutic efficacy of neuroleptics suggests also that hyperactivity of dopaminergic transmission is involved in the pathophysiology of hysterical neurotic symptoms.