In acute osteomyelitis of childhood a rapid diagnosis and initiation of antibiotic therapy is necessary in order to prevent late sequelae. Thus, diagnostic imaging plays a crucial role. If acute osteomyelitis is suspected in a child, imaging starts with conventional radiography in order to exclude other differential diagnoses. This is followed by sonography for the purpose of diagnosing a subperiosteal abscess or joint fluid from which the causative organism could be isolated. If the diagnosis is unclear, the next step should be either MRI or 99m Tc-MDP bone scan, depending on the possibility of clinical localization and the site of the suspected lesion. MRI is superior to bone scan in depicting the exact anatomy, which is extremely important in spinal osteomyelitis and preoperatively. The bone scan can show the whole skeleton in one examination and should be favored if there is no definite localization or in suspected multifocal osteomyelitis. Rarely scintigraphy with labeled white blood cells is indicated. The 67 Ga scan, however, should not be used in children because of the high level of radiation exposure. The different imaging modalities are described in detail and an imaging diagnostic workup is outlined.