Meckel's syndrome is an autosomal recessive disorder classically defined by occipital encephalocele, multicystic kidneys and polydactyly. However, a very wide phenotypic spectrum is characteristic of Meckel's syndrome. The prenatal diagnosis of this lethal syndrome is approached with ultrasound examination. The karyotype has to be done in order to make the differential diagnosis, especially with Trisomy 13 or 18. The rate of the Meckel's syndrome's gene is 1/400. The isolation of the specific gene will be soon helpful to define the Meckel's syndrome precisely.