Pyomyositis has become an increasingly recognized disease in temperate climates. A patient receiving chlorambucil for progressive systemic sclerosis, in whom streptococcal pyomyositis developed, is presented. Magnetic resonance imaging led to the early diagnosis. To our knowledge, this is the first case report of pyomyositis in a patient with scleroderma, and the first association with group G streptococcus infection in an adult. Connective tissue diseases and immunosuppression may emerge as risk factors for the development of this entity.