Sporadic inclusion body myositis is a common acquired inflammatory myopathy in people over 50 years of age. It presents with slowly progressive asymmetric weakness that affects preferentially the quadriceps and deep finger flexors. The pathogenesis is poorly understood. The diagnosis is made with a combination of the clinical history, physical exam, electrodiagnostic tests, imaging, serology and histopathology. There is no treatment for this condition but multiple therapies are currently being investigated.