Major changes have occurred in the epidemiology of community-acquired pneumonia recently. The emergence of new pathogens emphasises the need for continued vigilance in the diagnosis of pneumonia while changes in the microorganism or in the host have resulted in exciting new aspects of several old pathogens. Clinical and radiologic signs are unreliable in predicting the infecting organisms. Thus initial therapy is nearly always empiric. This approach often requires good clinical judgement and a knowledge of local epidemiological patterns in choosing an appropriate regimen. State-of-the-art invasive diagnostic procedures are usually reserved for pneumoniae that fail to resolve with initial treatment. Non-specific measures like stabilisation of underlying medical conditions, adequate nutrition and cessation of smoking or alcohol may help prevent the development of community-acquired pneumonia. On a larger scale, influenza and pneumococcal vaccinations are cost-effective preventive measures.