Primary peritoneal tumors are rare and yet not well-known malignancies. We report here the clinical cases of 8 patients who were referred to our institution with a primary peritoneal tumor, 4 serous carcinomas (PSC) and 4 malignant mesotheliomas (PMM). Diagnosis was available in all cases and reviewed by two pathologists. A battery of various immunomarkers contributed to confirm the morphological diagnosis. All patients underwent initial surgery with or without optimal debulking. All of them received a platinum-based systemic chemotherapy. Intraperitoneal treatment with cisplatin and hyperthermia was performed in two cases. Four patients are dead (3 PSC, 1 PMM), two are alive (one in partial remission (1 PSC) and one is having treatment (1 PMM)), one is in complete remission (1 PMM) and one is lost to follow up (1 MMP). PSC and PMM are difficult to distinguish since they share the embryonic cOElomic epithelium as a common origin. The clinical presentations are similar and usually include the detection of a pelvic mass and/or diffuse peritoneal carcinomatosis with or without malignant ascites. Therefore, the accuracy and reliability of the initial histological examination is of crucial importance. Further attempts will be required to better identify the most active therapeutic post-surgical combinations, especially for PMM.