BACKGROUND Chylous effusions are the most frequent cause of non immunologic hydrops fetalis. They can be recognized antenatally by ultrasonography. Their evacuation is sometimes necessary and medical treatment often effective. METHODS Case n. 1: fetal ascites was detected by ultrasonography at the 30th week of gestation. Paracentesis was performed at 36 weeks, followed 3 days later by spontaneous delivery. The newborn was fed milk formula. A second paracentesis showed a milky fluid, rich in cholesterol, triglycerides and chylomicrons. The child was fed formula rich in medium-chain triglycerides and the chylous ascites disappeared completely within 2 weeks. Case n. 2: a diagnosis of bilateral hydrothorax and hydramnios was made at the 27th week of gestation. An in utero evacuation of the hydrothorax performed at the 30th week was ineffective and a pleuro-amniotic drainage was performed 2 weeks later. The baby was born at the 35th week, and presented a moderate respiratory distress due to the hydrothorax and ascites. Aspiration of the thoracic fluid confirmed its chylous origin. The chylous effusions completely disappeared when the child was fed a high medium chain triglycerides diet. A lymphedema of legs appeared at the age of 1 month. Case n. 3: ascites, hydramnios, hydrothorax and peripheral edema were found at the 21st week of a third pregnancy (the 2 first pregnancies were complicated by lethal hydrops fetalis). Bilateral hydrothorax and peripheral edema were found again after birth at the 37th week. Diuresis and albumin-infusion led to recovery, but chylothorax and chylous ascites reaccumulated after introduction of milk formula, despite repeated evacuations and feeding medium-chain triglycerides formula. The thoracic fluid remains chylous at the age of 9 months. CONCLUSIONS In utero, and sometimes post-natal, evacuation of fluid present in the thoracic and peritoneal cavities can be necessary, depending of the functional tolerance. Medical management including feeding a low fat and/or high medium-chain triglycerides diet, and sometimes temporary total parental nutrition, is necessary, together with salt restriction, diuresis and albumin infusion as required. Most cases recover spontaneously or as a result of therapy within a few weeks.