Abstract 3 cases of fetal megacystis have been described in the article. In each clinical situation the pathology was diagnosed in the first half of the pregnancy. The authors have attempted to present clinical management in congenital megacystis. Key elements in the further diagnostics of megacystis in a fetus include invasive procedures to exclude or confirm chromosomal aberrations in fetus and detailed ultrasound anatomy scan of the fetus. The possibility of prenatal treatment of megacystis (placement of vesico-amaniotic shunt) is the source of considerable controversy. Biochemical assessment of fetal kidney function seems to be the most important element in evaluation of patients before introducing the intrauterine therapy. Contraindication for the prenatal treatment may be not only fetal aneuploidy but also serious maternal pregnancy complications, such as severe preeclampsia accompanied by deterioration of renal function and increasing ascites. The decision to place the shunt in a fetus should be made bearing in mind that although it significantly reduces the risk of perinatal death, it may unfortunately fail to improve renal function of the affected child.