The thoracic vent is a new minimally invasive device for the treatment of spontaneous and iatrogenic pneumothorax. It consists of a polyurethane catheter connected to a plastic chamber containing a one-way valve. As there is no need to connect the thoracic vent to an underwater seal device, immobilization and hospitalization can be avoided. So far the performance of the thoracic vent has been evaluated only in patients without pleural effusions and without signs of tension pneumothorax. Hence, we have performed a randomized study comparing the treatment of pneumothorax by means of the thoracic vent versus conventional intercostal tube drainage in 30 patients, including some with tension pneumothorax. 17 patients were treated with the thoracic vent, 13 with conventional intercostal tube drainage. We found no significant differences in the rate of reexpansion and rate of complications between the group treated with the thoracic vent and the group treated with intercostal tube drainage, but the patients treated with the thoracic vent needed significantly less analgesics. 70% of the patients treated with the thoracic vent were successfully managed on an outpatient basis. All patients treated with intercostal tube drainage were hospitalised; duration of inpatient-therapy was 8 +/- 6.2 days (mean +/- SD).