Peritoneal tuberculosis is uncommon today. Its symptoms are insidious and non-specific, simulating symptoms of peritonitis carcinomatosa. We report the case of a 35-year-old woman with ascites and elevated serum CA-125 levels, in which explorative laparotomy with the previsional diagnosis of ovarian carcinoma, revealed peritoneal tuberculosis. After treatment with bacteriocidal chemotherapeutic agents, the serum CA-125 returned to normal, and the patient has been well for 12 months postoperatively. Serum CA-125 levels are elevated in the case of peritoneal tuberculosis, and the possibility of this rare pathology should always be considered in patients with a previsional diagnosis of peritonitis carcinomatosa.