We report a case of psoas abscesses associated with systemic sclerosis and rheumatoid arthritis. A 61year-old woman had been sufferring from high fever. A computed tomography (CT) scan revealed bilateral psoas abscesses from which Peptostreptococcus spp. were detected by a culture of the pus. The abscesses were ameliorated by performing CT-guided percutaneous drainage and using appropriate antibiotics. Although psoas abscess is relatively rare, it can be a cause of fever of unknown origin in collagen diseases.