Suspect pleural effusion in any patient who has dyspnea, dry cough, or pleuritic chest pain associated with loss of tactile fremitus on physical examination. Plain chest films are valuable in confirming the presence of effusion, providing clues to the cause, and directing the method of pleural fluid sampling. Thoracentesis is safe and simple, and it is diagnostic in about 75% of cases. Unexplained exudative effusion is an indication for pleural biopsy, which usually reveals malignancy or tuberculosis. Thoracoscopy permits visually directed pleural biopsies and allows for therapeutic intervention at the time of diagnosis, obviating the need for subsequent invasive procedures.