Efficacy and safety of fedotozine (FZ), a peripheral K agonist, were compared to that of placebo (PL) in patients with functional dyspepsia. Methods. A phase Ill, double blind, parallel group trial was carried out in UK and Eire by 25 hospital or general practice centers. The entry criteria were: presence of 2 or more post-prandial dyspeptic symptoms occurring at least 3 times a week in the previous 3 months; the symptoms included epigastric pain, early satiety, epigastric fullness or distension, nausea or vomiting, feeling of slow digestion. Each patient had negative gastroduodenoscopy, upper abdominal ultrasound and routine blood tests. Patients completed a diary card daily and rated the overall intensity of their symptoms (main criterion) as well as the intensity of each dyspeptic symptom using a 5 point scale. 333 patients entered the trial. At the end of the run-in period lasting 7 to 14 days, patients with a low symptomatic score were excluded. 271 patients (139 F/132 M, aged 42 ± 14 yrs, m ± SD) were randomized to receive either oral FZ, 30 mg tid (n = 140) or PL tid (n = 131) for 6 weeks. Intent-totreat analysis was performed comparing the mean over the 6wk treatment adjusted for the baseline value (ancova). Results. FZ and PL groups were comparable before treatment. During treatment, the improvement for the overall intensity of dyspeptic symptoms was significantly higher (treatment effect: 0.180; 95% Cl: 0.07 to 0.29; p = 0.002) on FZ group than on PL. So too were epigastric pain (p = 0.004) and nausea (p = 0.01). The difference for sensation of fullness was of borderline statistical significance (p = 0.052). The patient global score, average of the five individual symptoms, was significantly improved in the FZ group (p = 0.021). There was no significant difference in the incidence of adverse events. The number of withdrawals associated with adverse events was comparable on FZ (n = 13) and on PL (n = 10). Biological tolerance was similar for both groups.