A case of non-tropical pyomyositis (PM), in a 63-year-old female patient, affecting gluteus and intrapelvic muscles is presented. Delayed diagnosis and treatment led to long-standing morbidity. Magnetic resonance imaging (MRI) of the pelvis provided valuable information on the nature and extent of the disease and helped to plan surgical management. MRI of the pelvis should be undertaken at an early-stage. Prompt examination of material obtained by aspiration or debridement would then permit an accurate diagnosis and appropriate management.