Pneumonia is more frequent in the elderly and results in higher morbidity and mortality. Although the incidence of pneumonia increases with age, from 1 per 1,000 to 12 per 1,000 persons over age 75 years, comorbid medical illnesses and host defense impairments (especially heart disease, chronic obstructive pulmonary disease, and aspiration risk) are independent risk factors. The microbial etiology of pneumonia in the healthy elderly is similar to that in younger patients but shifts toward a more gram-negative and opportunistic flora with increasing age and severity of concomitant medical illness. The choice of antimicrobial therapy must be based on risk stratification (age, medical illnesses, and severity of presentation). Guidelines based on these principles will be reviewed. Pneumococcal and influenza vaccination reduce the risk of death due to pneumonia and are cost-effective preventative strategies.