Some authors suggested that MR imaging could represent an effective diagnostic alternative in the study of pathologic conditions of mother and fetus during pregnancy. To verify the actual role of MR imaging, we examined 20 patients in the 2nd and 3rd trimester of gestation, after a preliminary US examination. Fifteen patients presented fetal or placental pathologies; in 4 patients the onset of the pathologic condition occurred during pregnancy; in 1 case of US diagnosis of fetal ascites, MR findings were normal and the newborn was healthy. As for placental pathologies, our series included a case of placental cyst, two hematomas between placenta and uterine wall, and two cases of partial placenta previa. As for fetal malformations, we evaluated a case of omphalocele, one of Prune-Belly syndrome, a case of femoral asymmetry, one of thanatophoric dwarfism, a case of thoracopagus twins with cardiovascular abnormalities, two fetal hydrocephali, and three cases of pyelo-ureteral stenosis. As for maternal pathologies during pregnancy, we observed a case of subserous uterine fibromyoma, one of right hydronephrosis, one of protrusion of lumbar intervertebral disk, and a large ovarian cyst. In our experience, MR imaging exhibited high sensitivity and a large field of view, which were both useful in the investigation of the different conditions occurring during pregnancy. In the evaluation of fetal and placental abnormalities, especially during the 3rd trimester, the diagnostic yield of MR imaging suggested it as a complementary technique to US for the evaluation of fetal malformations and of intrauterine growth retardation.