The authors examine the variations of PRL plasma levels after the administration of sodium thiopentale 500 mg i.v. to ten patients undergoing voluntary pregnancy interruption between the 8th and the 14th gestational week; PRL levels which were already elevated due to estrogen action, as is physiological in pregnancy, further increased after the anaesthetic drug injection confirming the ability of sodium thiopentale to increase prolactin levels even in estrogen-induced hyperprolactinemic conditions; the possible ways through which the drug may act are then discussed.