Pneumocystis carinii pneumonia (PCP) is the major pulmonary complication in patients with the acquired immunodeficiency syndrome. While fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) and transbronchial biopsy (TBBX) is regarded as the procedure of choice to identify PCP, these techniques, particularly TBBX, pose potential risks to the already compromised patient. To reduce the duration of bronchoscopy and, hence, lessen the chance for complications, we describe a rapid technique to identify PCP in BAL fluid by cytocentrifugation and hematoxylin-eosin staining. By this method, PCP can be easily diagnosed within 10 min. The sensitivity of this rapid diagnostic procedure is 95.7%, and the specificity is 100%.