The advantages and limitations of MRI in lung infections in children have not been well established. This article illustrates the MRI findings in children with pneumonia caused by Mycoplasma pneumoniae, Streptococcus pneumoniae, and other pathogens. Lung parenchymal, pleural, and lymph node abnormalities are well characterized by MRI. Loculation of pleural fluid is detected in children with empyema. Contrast enhancement may be useful in the differentiation of active inflammation from noninflammatory changes. MRI can be particularly useful in the follow-up of children with chronic pulmonary diseases.