DEMONS-MEIGS syndrome is defined by a pathological triad associating ascites, hydrothorax (Both can sometimes be associated) and an ovarian tumor, most often solid and benign but possibly cystic. Objective: To describe a case of Demons-Meigs syndrome observed at the Health Center of Reference of Markala. Clinical observation: We report the medical file of a 64-year-old postmenopausal lady, G11P7V6A0D1, IIG=2 years old without surgical history but poorly monitored hypertension. She was conducted in our department on 08/25/2020 in a picture of paroxysmal abdominal-pelvic pain with gravity type associated with an alteration of the general condition. It is associated with a productive cough with dyspnea of effort and previous chest pains. After the physical examination, there was a voluminous rounded pelvic mass going from the epigastric region to the pubic hair, the ultrasound examination having objectified an ascites of medium abundance and a voluminous left pelvic mass of 191mm / 120 mm then the chest X-ray from the front showing a right basal pleural effusion, the diagnosis of Demons-Meigs syndrome was evoked. After a preoperative assessment and a pre-anesthetic consultation, an exploratory laparotomy was performed. At the celiotomy, a serohematic ascites of 1.5 l is discovered, a large ovoid and pediculated ovarian tumor of the left ovary, not bumpy, overhanging the uterus, not twisted and not adhered but easily mobilizable. Conclusion: The Demons-Meigs syndrome which essentially comprises a benign ovarian tumor, ascites and a recurrent pleural effusion, characterized by healing without sequelae with drying of the effusions (Ascites and pleurisy) after removal of the ovarian tumor still retains a rather obscure etiology and pathophysiology.