OBJECTIVE To explore the clinical features, pathologic characteristics and prognosis of double primary malignant tumors with involvement of the stomach and an extragastric site. METHODS We reviewed the records of 496 patients who underwent surgery for gastric cancer in our department from January 2004 to December 2006. Synchronous double primary cancer was defined as an extragastric cancer diagnosed within a 6-month interval before the detection of gastric cancer; any gastric cancer metastasis to other areas of the body was excluded. RESULTS Synchronous and metachronous double primary cancers were identified in 1 and in 5 patients, respectively. The extragastric sites of the primary tumors in patients with gastric cancer were esophagus in 1 case, right colon in 1, rectum in 1, breast in 2 and lung in 1. Following gastric surgery, 5 patients died (within 2 mon, 24 mon, 30 mon, 48 mon and 60 mon). Only 1 patient has survived and remains disease free. CONCLUSION The prognosis of patients with gastric cancer and a second primary is relatively poor. It is necessary to perform regular esophagogastroduodenoscopy (EGD) on patients who have been diagnosed with extragastric cancer, regardless of their symptoms.