The pharmacokinetics of etoposide (VP 16) and teniposide (VM 26) were studied after intrapleural administration to 3 patients with lung cancer and malignant pleural effusion. Comparison with the kinetic behavior of intravenously infused VP 16 and VM 26 in the same patients suggests that intrapleural drug delivery achieves higher and longer-lasting pleural concentrations, thus providing a theoretical basis for the palliative treatment of malignant pleural effusions. Although no systemic toxicity was observed after intrapleural administration of either drug, 1 of the 3 patients developed a transient asymptomatic hemorrhagic pleurisy during the first 2 days after the drug, alerting to the possible local toxicity of such treatment.