BACKGROUND: For the evaluation of infectious or inflammatory disease, Tc-99m HMPAO WBC scan has been used. But techniques involving radiolabelled leukocytes scan were difficult, and have failed to distinguish between bacterial infection and non-bacterial inflammation. To overcome this difficulty, we evaluated Tc-99m Ciprofloxacin in clinically suspected bacterial infection. METHODS: We used this agent for 31 patients who had suspected sites of infection. And then we compared the imaging results of these patients with those of radiolabelled leukocyte scan. RESULTS: There was no adverse effect. 29 patients was involved for the interpretation. Infective spondylitis was the most common suspected disease (41%). Bateriologic culture was positive in 10 patients. The most common organism was meticillin-susceptible S. aureus (5 cases). The sensitivity and specificity of Tc- 99m Ciprofloxacin was 83.3% and 66.6%, and those of Tc-99m HMPAO WBC was 62.5% and 83.3%, repectively. For the diagnosis of infective spondylitis the sensitivity of Tc-99m Ciprofloxacin was 80.0% and that of Tc-99m HMPAO WBC was 40.0%. CONCLUSOIN: Tc-99m Ciprofloxacin shows relatively high sensitivity and specificity. Tc-99m Ciprofloxacin was superior to Tc-99m HMPAO WBC for the diagnosis of infection in axial skeleton.