The efficacy and safety of the peripheral kappa-receptor agonist fedotozine was investigated in a double-blind, placebo-controlled, dose-ranging study involving 146 patients with nonulcer dyspepsia (NUD). After a two-week washout, patients were assigned to one of four groups to receive either placebo or fedotozine three times a day at doses of 10, 30, or 70 mg for six weeks. Analysis of mean symptom intensity scores showed that the 30-and 70-mg doses of fedotozine were superior to placebo in relieving postprandial fullness, bloating, abdominal pain, and nausea. Eructation and early satiety were marginally affected. The 30-mg dose was significantly more effective than placebo in reducing the total symptom score. Eight-two mostly minor adverse effects were recorded, but no significant differences in distribution emerged between placebo and treatment groups. The number of withdrawals declined significantly as a function of increasing dose. These results indicate that 30 mg three times a day is the minimal effective dose of fedotozine in the treatment of NUD symptoms and that this treatment is safe.