70 patients with confirmed (23 patients) or suspected (47 patients) bacterial infection in the skeleton following diseases, injuries or operations in orthopedic surgery were investigated using Tc-99m-HMPAO leucocyte scintigraphy in order to evaluate the accuracy of this procedure. Infections could be detected correctly in 37 of 70 patients (right positives) while 28 patients had negative scans corresponding to the clinical course (right negatives). One false negative finding was observed. Five patients with clinically suspected infection had a focal uptake in the WBC-scan and were not operated subsequently. They range as false positive results, although they belong to a special group (Infection: Yes-Operation: No [IYON]-group). In the assessment of the Tc-99m-HMPAO-WBC-scan there was a senstivity of 97.1%, specificity of 82.9% and an overall accuracy of 90%. The method is suitable for detection of early and late infection as well as chronic or hematogenous osteomyelitis in the locomotor system. This means an important contribution in diagnosis of infection determining further operative or conservative treatment.