Somatostatin (SS-14; growth hormone-release inhibiting hormone) was infused into eight patients with non-toxic sporadic goiter and into eleven normal control subjects. Each patient was given 150 microgram(s) of somatostatin as an intravenous bolus and 350 microgram(s) by infusion over a period of 60 minutes. Somatostatin did not lower the basal TSH levels as compared to the pre-infusion levels in this type of goiter, but produced a decrease in the TSH response to TRH during and after the infusion.