PURPOSE The purpose of this study was to evaluate the diagnostic value of Tc-99m-labeled antigranulocyte antibody fragments in the diagnosis of osteomyelitis. MATERIALS AND METHODS Thirty immunoscintigrams were evaluated retrospectively with 740 MBq (20 mCi) Tc-99m-labeled antigranulocyte antibodies. The final diagnoses were confirmed by histology, magnetic resonance imaging, computed tomography, and clinical follow-up. RESULTS In the retrospective analysis, 20 of 30 patients (67%) demonstrated a true-positive result. Three of 30 patients (10%) had a false-positive result. A false-negative result was found in a diabetic patient with a perforating ulcer of the foot. Six of 30 patients had a true-negative result. A high sensitivity of 95%, a relatively high specificity of 67%, and a high diagnostic accuracy of 86% were present in this study. CONCLUSION Tc-99m labeled monoclonal antibody-Fab' fragments are suitable for the detection of osteomyelitis. Its clinical application is simple. Its use guarantees a reliable and accurate diagnostic result just 1 to 2 hours after injection, making a late scan unnecessary. Coxarthrosis or hyperostosis can lead to false-positive results. A perforating ulcer of the foot may result in a false-negative conclusion.