Sixty-seven patients with disseminated cancer were randomly allocated to treatment with continuous closed chest drainage removing all fluid for 72 hours (PD) or pleural drainage for 72 hours with the instillation into the pleural space of radioactive colloidal chromic phosphate (PD + 32P). Forty-nine patients had breast carcinoma, and the remaining 18 patients had other cancers. Four of 49 patients with breast cancer and 13 of 18 with other cancer were dead in 8 weeks from the onset of effusion. In the group of patients with breast cancer PD + 32P controlled the effusion in 12 of 22 (54%) and PD alone in 15 of 30 episodes (50%). In the nonbreast group of patients PD + 32P controlled the effusion in five of six evaluable episodes (83%), and PD alone was successful in two of nine (22%). In 33% of breast cancer patients and 25% of the nonbreast-cancer patients, systemic chemotherapy produced objective remissions. Pleural effusion did not recur in any of these patients.