17 obese women were examined, 8 of which were diabetic and 9 affected only by essential obesity. These patients, all of whom had become obese during adult life and 8 control subjects were tested for IRI, GH and PRL levels in basal conditions and after infusion of TRH. In the obese and diabetic women fasting GH values were normal while IRI levels were higher than those of the control subjects. In all cases neither IRI nor GH variations during TRH stimulation test. There was no difference in the plasma levels of PRL between the 3 groups when examined in basal conditions. After TRH the hormone increased considerably in all the subjects. In the obese and diabetic obese women the incremental area did not present different values from those observed in the control subjects. In conclusion in insulin-independent diabetes, as in essential obesity, the pharmacological stimulus did not show any evident alteration of the specific hypofisary receptorial system that regulates the secretion of PRL and GH.