Background: Inflammatory myopathies are a complex heterogeneous group of disorders in the field of rheumatology. Muscle biopsy is the cornerstone of differential diagnosis. Objective: The aim of this study was to compare the diagnostic yield of needle muscle biopsy using large bore pleural biopsy needle with conventional open surgical biopsy. Methods: Needle muscle biopsy (NMB) using large bore pleural biopsy needle and conventional open surgical biopsy of muscles were carried out on all of the 32 patients referred to Hazrat-rasool Hospital in 18 months period with suspected inflammatory myopathies. Results: The pathologic reports were similar in 27 out of 32 patients. 4 samples were reported normal by both methods. One technical problem occurred in needle biopsy and one vasculitis case was misinterpreted as inflammatory myopathy. However, results were significantly different in respect to disadvantages by the two methods (p=0.021). Conclusion: Needle muscle biopsy with large bore pleural biopsy needle can be used as an early diagnostic tool for evaluating patients with suspected inflammatory myopathies