Somatostatin (ST) inhibits gastrointestinal motility and exocrine and endocrine secretions. In animals, ST has been demonstrated to decrease food intake. We investigated, in a randomized double-blind investigation in 10 healthy humans, the effects of an intravenous ST infusion compared to saline on subjective hunger feelings. After 1 h, a low dose of fat was given intraduodenally to induce the release of endogenous upper-intestinal satiety factors. Ninety minutes later sandwiches were served and eaten until satiation. In the first hour, when no intraduodenal fat was given, there was a significant decrease in feelings of hunger with ST (p < 0.05). During the intraduodenal fat infusion this pattern reversed with a trend towards less satiety with ST. Food intake during intraduodenal fat infusion tended to be higher during ST (305 +/- 42 g) than during saline (205 +/- 36 g) although not significantly. In the 5 h after the experiment hunger feelings were significantly less after ST. In conclusion, we found evidence for a satiety effect of ST in humans which reversed towards less satiety when intraduodenal intralipid, which presumably produced endogenous satiety factors, was given. Postmeal satiety is higher after ST.