During a one-year epidemiologic survey of acute community-acquired pneumonia, we prospectively investigated in 116 adult nonimmunocompromised patients (a) the importance of initial noninvasive investigations (ie, blood culture and quantitative sputum culture) and the value of the initial radiologic type of pneumonia in diagnosing of the etiologic agent, and (b) the management of pneumonia. Quantitative sputum culture or blood culture (or both) permitted bacteriologic diagnosis in 44 percent of the cases. The radiologic types found were segmental or alveolar densities in 75 patients (65 percent), patchy alveolar densities in 11 (9 percent), mixed opacities in 26 (22 percent), and interstitial infiltrates in four (3 percent). We observed that (a) the prognosis was identical whether a bacteriologic diagnosis was made or not, (b) the Gram stain, an inexpensive procedure, was as contributive for bacteriologic diagnosis as quantitative sputum culture, diagnosis as (c) blood cultures were poorly contributive in patients without severe infections, and (d) alveolar densities were associated with a bacterial infection in 90 percent of the cases of known etiology. On the basis of these results, a pragmatic strategy of initial management of community-acquired pneumonia is proposed.