We present a rare case of a 46-year-old man presenting with mucinous ascites secondary to malignant peritoneal mesothelioma (MPM) that was diagnosed via colonoscopy with biopsies. Both our findings and the clinical presentation were unique. While it is widely known that asbestos exposure is commonly associated with pleural mesothelioma, 6-10% of malignant mesotheliomas arise from the peritoneum. To date, only 4 cases of MPM with the primary tumor site in the colon have been described in the literature.