Recurrent pneumonia is defined as two episodes of pneumonia in 1 year or three episodes over any time frame. Nonresolving pneumonias are characterized by the persistence of symptoms and roentgenographic abnormalities for more than 1 month. The key step in evaluating the patient referred for recurrent or persistent pneumonia is to review the clinical and radiographic features of the episodes to determine if there is adequate documentation to proceed with treatment. After deciding that a patient has had a persistent episode of pneumonia or the requisite number of recurrent episodes of pneumonia (accompanied by radiographic evidence of pulmonary infiltrates), it is essential to classify the episodes into those involving single or multiple lobes. On the basis of this classification, the differential considerations and subsequent evaluation are determined.