Pleural effusions are common in the setting of lung cancer. A pleural effusion associated with lung cancer is an ominous finding, but a small percentage of patients are candidates for curative surgery. The clinician must establish whether the effusion is malignant, excluding the possibility of curative surgery; paramalignant, which may or may not exclude surgery; or whether it is unassociated with cancer. When a malignant pleural effusion is diagnosed, the clinician must decide on the most appropriate form of palliation for the symptomatic patient. In the symptomatic patient with a reasonable life expectancy and pleural fluid pH of more than 7.3, chemical pleurodesis appears to be the most effective and least morbid therapy.