Muscle biopsy can be used to confirm the diagnosis of neuromuscular diseases. However, it is unclear whether antibiotic prophylaxis prior to muscle biopsy is needed to prevent surgical site infection (SSI). We are conducting a phase 2, single-center, open-labeled, prospective randomized trial to clarify the need for antibiotic prophylaxis in patients at low risk for SSI undergoing muscle biopsy. Patients will be randomized to an antibiotic prophylaxis group or a control group, and the incidence of SSI will be compared between the groups. Our findings will clarify the need for antibiotic prophylaxis in this patient population.