The cases of 3 patients with pyomyositis associated with hematological disorders are reported. A 40-year-old man in the blastic phase of chronic myelogenous leukemia and 2 men aged 46 and 71 years with neutropenia due to myelodysplastic syndromes all reported high fever and severe local myalgia and had marked elevation of C-reactive protein. Magnetic resonance imaging revealed muscle abscesses or fasciitis, and the findings led to the diagnosis of pyomyositis. Methicillin-resistant Staphylococcus aureus was isolated from the abscesses of 2 patients, and surgical drainage proved more effective than did antimicrobial agents. It should be recognized that pyomyositis is a possible source of infection in patients with hematological disorders.