In clinical practice, H2-receptor antagonists, including nizatidine, in addition to their use in the treatment of peptic ulcer and gastroesophageal reflux, are also useful in alleviating dyspeptic symptoms. Patients with functional dyspepsia show a tendency to delayed gastric emptying. Results of preliminary studies have demonstrated that nizatidine has a prokinetic effect due to its cholinergic properties. The aim of this study was to evaluate the effect of nizatidine on gastric emptying in patients with functional dyspepsia. Sixteen patients with dyspeptic symptoms referred for gastroscopy by primary care physicians were enrolled in this randomized, placebo-controlled, double-blind cross-over study. They received nizatidine 150 mg twice daily or placebo for 2 months. After a 1-month washout period, the 2-month treatment was repeated, with these patients acting as their own controls. Gastric emptying was measured by scintigraphy, and dyspeptic symptoms and quality of life were evaluated at the end of both treatment periods. Gastric emptying of solids during nizatidine therapy was prolonged (T1/2 110.1 +/- 76.7 vs. 65.6 +/- 23.2 min, P = 0.03), but nizatidine had no effect on gastric emptying of liquids. Nizatidine improved the symptom scores and seven of eight aspects of quality of life - but not significantly. In conclusion, nizatidine decreases the gastric emptying rate of solids without having a significant effect on symptoms or quality of life in functional dyspepsia.