In this case report a patient with triple synchronous tumors: gastric adenocarcinoma, gallbladder adenocarcinoma, and adenocarcinoma of the sigmoid colon has been presented. An 86-year-old female patient with a history of weight loss and epigastric pain was admitted to our department. Her upper gastrointestinal endoscopy and colonoscopy showed a 2 cm-sized polypoid mass in the posterior wall of the gastric antrum and a 3,5 cm-sized tumor in the sigmoid colon. A third tumor was detected in the gallbladder by ultrasonography and tomography. In the same operation, all tumors were removed by sigmoid colon resection, cholecystectomy, and subtotal gastrectomy. Stages of tumors were for gastric adenocarcinoma (pT1N0), gallbladder adenocarcinoma (pT1N0), and sigmoid adenocarcinoma (pT4N0). 14 months after surgery the patient was re-operated due to ileus caused by recurrence of colonic tumor. Left hemicolectomy, partial resection for adhesion of the small intestine, and side-by-side anastomosis were performed. In the intensive care unit, the patient died of cerebrovascular incident after 4th day of surgery. The chance of finding multiple primary malignancies should always be thought of throughout the treatment and follow-up of elderly cancer patients. The physician should be alert to the possibility of their occurrence to achieve proper treatment.