MR examinations were performed in 9 patients suffering from severe pain of the hip during the third trimenon without any relief after birth. Pathologic signal changes could be observed in 11 hips (oedema in the region of the femoral head and neck (n = 8); avascular necrosis of the femoral head surrounded by bone marrow oedema (n = 3)). In 7 hips a relatively rapid decrease of the oedema following core decompression was demonstrated. Focal necrosis, however, did not show any changes. In two patients, treated conservatively, markedly delayed healing was evident. MR imaging is the modality of choice for early diagnosis as well as follow-up of therapy of the bone marrow oedema syndrome or avascular necrosis and can be performed already during pregnancy.