To evaluate the diagnostic value of technetium-99m d, l-hexamethylpropylene amine oxime (HMPAO) labelled leucocytes in combination with a 99mTc-methylene diphosphonate (MDP) bone scan in the detection of chronic osteomyelitis, we retrospectively reviewed 55 patients. Prior to the 99mTc-d,l-HMPAO labelled leucocyte scan, all patients underwent a 99mTc-MDP bone scan. The correct diagnosis was confirmed by long-term clinical follow-up (n=29) or by bacteriological cultures (n=26). We found an overall sensitivity of 94%, a specificity of 91% and an accuracy of 92% for 99mTc-d,l-HMPAO labelled leucocyte scintigraphy in the diagnosis of chronic osteomyelitis. When the patients were divided into three groups according to the location of the infection, our study results showed a sensitivity and specificity for the central location (containing active bone marrow) of 94% and 100% respectively; for the peripheral location (hands and feet) both parameters were 100%, and for the middle location (all sites between the central and the peripheral location) the values were 92% and 81% respectively. Specificity and accuracy were significantly lower in the middle location than in the central and peripheral locations. The results of our study confirm that a 99mTc-d,l-HMPAO labelled leucocyte scan in combination with an 99mTc-MDP bone scan is a reliable way to diagnose chronic osteomyelitis, except for vertebral osteomyelitis.