Femoral head necrosis is a disfiguring disease of the hip joint that affects mainly young adults, mostly men in their 40s. The biggest problem with this disease is that if it is not detected early and treated properly, joint replacement is inevitable in about 80% of patients. Therefore, early diagnosis is the key point in the treatment of this disease. Currently, MRI is the most valuable tool to detect early femoral head necrosis, with high sensitivity and specificity. However, there is one disease that is often misdiagnosed as osteonecrosis of the femoral head because of the similarity between MRI and osteonecrosis of the femoral head, and this is transient osteoporosis of the hip. This disease is a self-limiting disease of unknown etiology, mainly seen in middle-aged men and women entering late pregnancy (after 28 weeks), presenting with pain in the hip, and plain radiographs often begin to show extensive osteoporosis about 2 months after onset. On MRI, there is extensive bone marrow edema in the femoral head, neck and even in the size of the trochanter, but this disease affects only unilaterally and does not show the characteristic “linear sign or double line sign” of the subchondral bone in the weight-bearing area typical of femoral head necrosis. In addition, non-traumatic osteonecrosis of the femoral head is often bilaterally affected in MRI, which is one of the main points of differentiation. TOH is a self-limiting disease that will gradually heal on its own in about 2-9 months after detection, and this process does not require special treatment, especially surgery, except for taking some analgesic drugs and avoiding weight-bearing on the affected limbs. There are often charlatans who take advantage of the self-healing characteristics of this disease to deceive patients about the effectiveness of their medications in treating osteonecrosis of the femoral head. And after the early diagnosis of this disease of femoral head necrosis, it is necessary to carry out active head preservation surgery in order to possibly avoid the collapse of the femoral head. Therefore, it is very important to accurately identify these two diseases, and once the patient has hip symptoms and abnormalities are found after MRI examination, he or she must go to a regular hospital to seek medical attention from a doctor with experience in this field and make a clear diagnosis before carrying out the correct treatment, so as not to be misdiagnosis.