A lung abscess is a circumscribed collection of pus in the lung as a result of a microbial infection, which leads to cavity formation and often a radiographic finding of an air fluid level. Patients with lung abscesses commonly present to their primary care physician or to the emergency department with "nonresolving pneumonia." Although, the incidence of lung abscess has declined since the introduction of antibiotic treatment, it still carries a mortality of up to 10%-20%. This article discusses in detail the up-to-date microbiology and the management of lung abscesses.