Magnetic resonance imaging (MRI) is a commonly used imaging modality to detect early avascular necrosis (AVN). When MRI is inconclusive, bone scan is helpful in detecting AVN during early phase of the disease. As newer nuclear medicine equipment, such as single photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography, are emerging in medical science, the role of these imaging modalities in AVN of femoral head is re-evaluated.