OBJECTIVE Steroids used especially during relapses of demyelinating diseases such as multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are a well-known risk factor for the development of avascular necrosis. The aim of this study was to evaluate the frequency of steroid-induced avascular necrosis (SIAVN) in our patients with demyelinating disease and the demographic, clinical and radiological features of these cases. Materials and Methods Patients with regular follow-up were screened from electronic patient records for the development of avascular necrosis retrospectively. Descriptive features of patients with avascular necrosis were evaluated. RESULTS SIAVN necrosis was detected in 7 (0.06%) of 1204 patients (6 with MS and 1 with NMOSD) who were regularly followed up in the demyelinating diseases outpatient clinic. Two of the patients had osteopenia before avascular necrosis. The mean cumulative steroid dose was 19.57±13.53 [minimum (min.) 7, maximum (max.) 44] grams. The mean time between the symptoms of avascular necrosis and diagnosis was 6±3.37 (min. 3-max. 12) months. Avascular necrosis was diagnosed in all patients by magnetic resonance imaging. Core decompression surgery was performed in 5 of the cases. CONCLUSION Avascular necrosis is a rare but important complication that can cause disability and should be recognized and treated early in the course of demyelinating diseases. It can develop independently of steroid dose and duration and is unpredictable, so it should be kept in mind especially in patients who develop hip or leg pain.