Osteomyelitis, which is caused by the infection of cancellous and cortical structures of the bone, is still a challenging disease for the orthopedic surgeons despite the advances in antibiotics and treatment options due to the propensity of the disease to recur and become chronic. The disease is classified as acute, subacute or chronic depending on the course and duration. Different types of the disease may manifest itself in the same patient at different times. Subacute osteomyelitis can occur after open fractures as well as after primary bone infections and is especially important in the older children and young patient populations. The clinical importance of the subacute osteomyelitis comes from the facts that it has nonspecific clinical findings and atypical localizations and its differential diagnosis from malign bone tumors may be difficult. Diagnosis is based on the clinical suspicion and Staphylococcus aureus is the major pathogen in these patients. Although currently there are valid medical and surgical treatment options, there are still no established treatment protocols in subacute osteomyelitis. Many treatment modalities like antibiotic treatment, surgical curettage, debridement and antibiotic-impregnated cement treatment can be performed. Despite todays advanced imaging and laboratory methods, there are still difficulties in the diagnosis of subacute osteomyelitis and its differential diagnosis from malignant lesions.