We describe our experience with two cases of acute gastric dilation after radiofrequency catheter ablation (RFCA) for supraventricular arrhythmia. After the RFCA procedure, patients experienced epigastric pain, abdominal distension, and vomiting. Computed tomography showed marked dilation of their stomachs, but without apparent obstruction of the gastric antrum or the duodenum. Esophagogastroduodenoscopy and upper gastrointestinal series revealed significant gastroparesis. We considered that gastric hypomotility had been induced by vagus nerve injury after RFCA. Peristaltic stimulants effectively improved the patients' symptoms by improving gastric motility. There have been few reports of acute gastric dilation after RFCA in Japan to date, but the possibility of encountering this condition is expected to increase in parallel with the recent increased use of RFCA. Therefore, gastroenterologists should be alert to this rare complication.