Based on three cases of foetal abnormalities (hydrocephalus, prune-belly syndrome, and unilateral multicystic renal disease) diagnosed and treated by intrauterine sonographic control, the article describes the technique, evolution and outcome of these cases. Two patients (the hydrocephalus and the prune-belly syndrome) died after delivery, whereas the third one lives in normal conditions. The different diagnoses and prognoses of this new surgical procedure are discussed. We think that hydrocephaly and renal obstruction have a very bad prognosis when diagnosis and therapy are not performed an initiated at an early stage. Unilateral disease of Potter-Syndrome is associated with a very good prognosis irrespective of whether therapeutic intervention is effected or not. For this reason, the intervention should be considered according to the compressive action that the cystic renal disease can exercise on the other kidney or lung.