Twenty-eight patients with chronic idiopathic dyspepsia defined by the presence of chronic unexplained symptoms suggestive of gastric stasis and directly related to food ingestion were included in this prospective study. Gastric emptying of the liquid and solid phases of a meal was quantified by a dual-isotope method, and symptoms were evaluated by a diary and a visual analog scale. Delay in gastric emptying was evidenced in 59% of the dyspeptic patients; it occurred with liquids in more cases than solids. Quantitative and qualitative evaluation of symptoms was of no practical value in predicting the presence of objective stasis. The dyspeptic patients were included in a double-blind randomized controlled trial of cisapride, a new gastrokinetic drug devoid of central antiemetic effects. After six weeks of cisapride treatment, all patients with initially abnormal gastric emptying rates for liquids, and all but one for solids returned to normal ranges, and significant differences between cisapride and placebo groups were observed for half emptying times of both solids (136 +/- 16 min vs 227 +/- 32 min; P less than 0.02) and liquids (61 +/- 4 min vs 132 +/- 37 min; P less than 0.01). Cisapride also significantly improved dyspeptic symptom scores at weeks 3 and 6 of treatment as compared to those measured before treatment. Nevertheless, the decrease in global diary score was significantly higher than that seen with placebo at week 3 (-16 +/- 6 vs -1 +/- 9; P less than 0.05), but not at week 6 (-18 +/- 5 vs -10 +/- 8).(ABSTRACT TRUNCATED AT 250 WORDS)