Various imaging modalities are used in diagnosis of acute and chronic infectious endogenous osteomyelitis and exogenous ostitis. The pathophysiological changes of osteomyelitis/ostitis in the bone and surrounding soft tissue are known. Findings in plain film radiography show these changes only in relatively advanced stages of disease. Hence, plain film radiographs are useful as a basic imaging modality by excluding other differentials and as a follow-up modality under therapy. Ultrasound-using advanced technology--offers diagnostic help in acute osteomyelitis, especially in infants. The various techniques of nuclear medicine show much higher sensitivity for detecting osteomyelitis than plain film radiography, but do not permit good separation for bone involvement and infectious changes in the surrounding soft tissue. While computed tomography offers the ability to display bone and soft tissue separately, it has been widely replaced by magnetic resonance imaging using fat-suppressed sequences and paramagnetic contrast media which show the spread of the infectious changes with higher sensitivity and accuracy.