Gastric carcinoma in the bypassed stomach after Roux-en-Y gastric bypass (RYGBP) is rare but has been reported. The time from RYGBP to the presentation of cancer has ranged from 5 to 22 years postoperatively in the literature. A major concern with the current technique for RYGBP is the exclusion of the bypassed stomach and difficulty in surveillance. Thus, some surgeons recommend routine preoperative evaluation via endoscopy. Although most findings are benign, abnormalities are frequently discovered during screening endoscopy in bariatric surgery patients. We present a 45-year-old woman who was discovered to have disseminated gastric cancer involving the excluded bypassed stomach following an open RYGBP. Preoperative upper endoscopy was not performed. This case illustrates the importance of endoscopic evaluation prior to RYGBP and signifies the need for a high index of suspicion in order to recognize this problem at an early stage.