The effect of dihydroergocryptine, a natural alkaloid derivative which exhibits D2 dopaminomimetic properties, has been studied in Lewis female rats with experimentally induced allergic encephalomyelitis. A chronic treatment with dihydroergocryptine started two days before immunization, induced a dramatic reduction of prolactin levels accompanied by a marked amelioration of neurological signs. In addition, the proliferative activity of splenic lymphocytes induced by the mitogen Concanavalin-A (Con-A) was reduced in dihydroergocryptine-treated animals. It is suggested that this effect is related to the ability of dihydroergocryptine to lower prolactin concentrations or also, partially, to a neuroprotective action of this drug.