Long term continuous oxygen therapy improves prognosis in patients with hypoxaemic chronic airflow limitation. Transtracheal delivery of oxygen permits adequate oxygenation of such patients at lower flow rates than are required for delivery by nasal cannulas, thus increasing the time for which portable oxygen cylinders can be used and improving the efficacy of domiciliary oxygen concentrators in patients with refractory hypoxaemia. In a study of the long term acceptability and risks of transtracheal oxygen in 37 patients, with a total follow up of 595 patient-months, most patients reported symptomatic benefit and four have used transtracheal oxygen successfully for more than four years. Problems have included surgical emphysema (4 patients), catheter fracture (9), local infection (34), and catheter dislodgement (21); but these have been relatively infrequent and in general have not caused important clinical problems. Transtracheal oxygen therapy was discontinued in 10 patients before death for various reasons, including infection (2 patients), catheter fracture (1), and surgical emphysema (1). Accumulation of mucus balls has not been a problem. It is concluded that transtracheal oxygen therapy is a safe and acceptable alternative to nasal cannulas in well motivated patients with hypoxaemia due to chronic airflow limitation who are keen to pursue an active life.