M. pneumoniae is a common cause of upper and lower respiratory tract infections in persons of all ages, including the very young and the very old. Extrapulmonary complications involving any organ system may accompany respiratory tract manifestations, or they may occur in persons without an obvious respiratory component to their illness. Clinical presentation is similar enough to other causes of respiratory infection that presentation alone cannot be used reliably to identify children in whom a mycoplasmal etiology is likely and coinfection with other bacterial or viral pathogens is common. Due to the many limitations of culture and serology, PCR is the preferred method for laboratory diagnosis, although it is not yet widely available in many countries. Macrolides have historically been the antibiotics of choice for children with mycoplasmal infections, but the emergence of clinically significant high-level resistance worldwide has necessitated a reevaluation of their use, particularly in locations where resistance is common. Consideration of alternatives such as tetracyclines and fluoroquinolones, even though these agents are not normally considered in younger children due to potential toxicities. © 2011 Springer Science+Business Media, LLC.