A rare case of carcinoid tumor in the duodenal bulb associated with early gastric carcinoma is reported. An 85-year-old asymptomatic male was admitted to our hospital, referred by his neighboring doctor because of early gastric carcinoma shown by endoscopic examination. X-ray studies of the upper gastrointestinal tract showed irregular lesser curvature of the gastric antrum and a filling defect (phi1 cm) at the duodenal bulb. Gastric biopsy revealed the histological findings of Group V. Distal gastrectomy including the duodenal bulb with D2 lymph node dissection was performed. A resected specimens showed superficial depressed type carcinoma at the lesser curvature of the antrum, and an isolated submucosal tumor of 7x7 mm in size at the duodenal bulb. Histological examination disclosed papillary adenocarcinoma in the gastric mucosa and a carcinoid tumor of the duodenal bulb in the submucosal layer without high malignant findings. The patient has been well for 5 years since the surgery. In conclusion, we discussed 46 collected cases of carcinoid tumor of the duodenum associated with gastric carcinoma in Japan. Preoperative diagnosis of carcinoid tumor of the duodenum is very difficult, and thorough examinations are needed for submucosal lesion.