Magnetic resonance imaging (MRI) is the most sensitive and accurate imaging modality in detecting bone changes due to avascular necrosis. Magnetic resonance imaging reaches nearly 100% sensitivity and specificity in diagnosing avascular necrosis. A serpiginous zone of low signal intensity (hypointense)on T1-weighted and T2-weighted images around the avascular area may be seen. On T2-weighted images, the appearance is in the form of a double-line sign which is characterized by an inner high signal intensity band and an outer low signal intensity band. The high intensity band in the doubleline sign represents the presence of cellular marrow area and live granulation tissue. In this article, we have mentioned MRI features of osteonecroses, differential diagnosis of oedema of femoral head and complications of osteonecrosis as well as avascular necroses (especially femoral head).