The problem of the differential diagnosis between subacute osteomyelitis and primary bone tumors is a difficult one. Presenting symptoms, duration of disease, laboratory data, and location of the pathologic process are of little assistance. The authors reviewed eight typical cases. Preoperative diagnosis included benign and malignant bone tumors, as well as osteomyelitis; but the final diagnosis of osteomyelitis was made only after open biopsy and culture. The presenting symptoms and signs included: pain, usually dull; soft tissue mass; and, rarely, low grade fever. The radiographic features were usually a lytic area with various degrees of sclerotic reaction. White blood count and sedimentation rate were not helpful. The treatment, including surgical curettage and appropriate antibiotic therapy, resulted in resolution of the process and healing of the bony defects.