MRI was first used 10 years ago for the study of fetal morphology. This non invasive technique is mainly advocated for the study of fetus brain. Principle indications for MRI are Examinations are performed at 0.5 and 1.5 Tesla. Minimal study consists of T2 sequences in the 3 dimensions and T1 in one. Maternal premedication using hydroxizyne dichlorhydrate (25mg) can be proposed to avoid fetal movements. The main advantage of MRI compared with US is to detect gyral and neuronal migration anomalies, cerebral signs, of tuberous sclerosis and recent hemorrhagic lesions.