Corticosteroids are the first-line treatment for patients with inflammatory myopathies. Myositis can be a clinical feature of scleroderma (polymyositis-scleroderma overlap syndrome), and treatment of this syndrome is a challenge for clinicians because moderate to high doses of corticosteroids are considered a risk factor for development of acute kidney injury in affected patients. We report here the case of a 56-year-old woman with scleroderma who developed polymyositis and was successfully treated with rituximab. Initial treatment of the polymyositis with prednisolone 40 mg/day was rapidly tapered to 2.5 mg/day due to development of scleroderma renal crisis, for which four weekly infusions of rituximab (500 mg; off-label) were given. She responded well to rituximab in addition to prednisolone 2.5 mg/day. Rituximab may improve inflammatory myopathies, even in cases where high-dose corticosteroids should be avoided due to complications. Rituximab should be considered as a treatment option in cases of refractory polymyositis.