Background: Osteonecrosis (ON) is a complex disease, and has been rarely reported. Vascular failure, metabolic changes, and sub-chondral fractures play an important role in the pathogenesis of ON. Case Report: Here, we present a case of 54-year-old male with knee osteonecrosis following a one month course of steroid therapy. Conclusion: Non-traumatic ON is a clinical case that occurs in rheumatologic and hematologic diseases depending on the chronic use of glucocorticoids. Additionally other underlying risk factors should be considered as seen in our case. If it is not diagnosed early, it can cause serious joint deformities and disabilities.