Spontaneous pneumothorax presents a high recurrence rate after conventional pleural drainage procedures. Different pleural scarifying agents are used in an attempt to prevent early and late recurrence. To investigate the effect of tetracycline and 30%-glucose, we conducted a randomized study on 20 patients with primary spontaneous pneumothorax: 10 patients were treated by pleural drainage combined with chemical pleurodesis; 10 patients were treated by pleural drainage alone. Chemical pleurodesis resulted in a statistically significant reduction (p less than 0.05) in early recurrence. The rate and magnitude of late recurrences however was unaffected by the pleurodesis treatment, although recurrence in the chemically treated group was later than in the conventional drainage group.