We examined the effect of oral cisapride on gastric emptying time and myoelectrical activity using real-time ultrasonography and cutaneous electrogastrography in 10 children with nonulcer dyspepsia. A clear dominant frequency close to 3 cpm was present both at baseline and after eight weeks of cisapride. After cisapride, nine children had an increase in the normal slow wave percentage and the mean percentage of normal slow wave was significantly different (71.90 +/- 5.19% vs 79.16 +/- 5.54%; P < 0.01). Moreover, an increased stability of the dominant frequency, determined by computing the coefficient of variation before and after cisapride, was found (28.12 +/- 1.72% vs 23.61 +/- 3.47%; P < 0.01). At baseline the gastric emptying time, expressed as T1/2, was 139.76 +/- 40.04 min and at eight weeks 119.76 +/- 30.04 min (P = 0.06). As regards the relationship between EGG and gastric emptying, the proportion of children with improved normal slow wave percentage was similar to that with improved T1/2 emptying (Z = 0.57, P = 0.57). Thus, gastric electrical activity seems to be an important factor in the pathophysiology of nonulcer dyspepsia in children.