Chronic obstruction of the proximal pulmonary arteries appears to be a rare complication of pulmonary thromboembolus. The syndrome, however, may prove to be more common than previously suspected as general awareness of the syndrome increases prompted by the availability of efficacious therapy. Medical management has been ineffective in providing symptomatic or consistent hemodynamic improvement in patients with this syndrome, but a growing body of literature now suggests that surgical relief of obstruction can be undertaken with acceptable surgical risk and with the expectation of dramatic clinical improvement in a selected group of patients. Although no true control groups exist, one might hypothesize that hemodynamic and clinical improvement may translate into improved survival in these patients as well. The most recent series reported by Daily et al7 is the first to include more than 100 patients, and their reported hospital mortality of less than 13% is very encouraging. Whether these results will be reproducible at other centers remains to be seen. It is hoped that future investigation will refine both patient selection and operative technique such that results continue to improve. Pulmonary physicians should be aware of the syndrome and have a high index of suspicion in patients with unexplained pulmonary hypertension or right-sided heart failure. V/Q scans have proved to be useful screening procedures in these patients and can help identify patients at risk who require further more invasive investigation.