The pathophysiology of gastrointestinal symptoms in patients with Fabry's disease is uncertain, despite the demonstration of histological and radiographic abnormalities of the gastrointestinal tract. The aims of this study were to determine if the gastrointestinal symptoms reported by patients with Fabry's disease are associated with abnormal gastric emptying and, if they are, whether prokinetic drug therapy would be beneficial. Ten patients with Fabry's disease had radionuclide gastric emptying studies performed to determine if gastrointestinal symptoms correlated with objective evidence of abnormal gastric emptying. A second study was performed in seven patients who received 5 days of therapy with oral metoclopramide. The mean percent solid gastric emptying for Fabry's patients was significantly less than that of a normal control group (40 vs 67%, P < 0.005). Five of seven patients with symptoms had abnormal gastric emptying. Six of seven symptomatic patients reported clinical improvement with metoclopramide. Of four symptomatic patients who had a repeat study after treatment, two showed improved emptying. In conclusion, our results suggest that gastrointestinal symptoms in Fabry's disease are frequently associated with delayed gastric emptying and that treatment with metoclopramide produces symptomatic and sometimes functional improvement.