BACKGROUND Coexistence of carcinoid tumor and colorectal adenocarcinoma is rare. In this report, we present two cases and review the current literature for synchronous carcinoid tumor and colorectal carcinoma occurrence. CASE REPORT In both cases, the rectal carcinoid tumors and sigmoid colon adenocarcinomas were detected by colonoscopy. The colon adenocarcinomas were effectively treated with a laparoscopic sigmoidectomy and the carcinoids were successfully removed endoscopically. Our 40-year-old patient was the youngest among 17 reported patient cases. CONCLUSIONS These two cases demonstrate that the diagnosis of gastrointestinal carcinoid requires a complete assessment of the remainder of the colon for another primary cancer to achieve a timely treatment management strategy.