An epidural type catheter was placed in the pleural space under direct vision before the closure of the chest in 24 patients who underwent thoracotomy for various types of lung or aortic surgery. All patients received intrapleural injections of 20 ml of 0.5 per cent bupivacaine with or without epinephrine as initial pain therapy. Patients also received subsequent doses of a similar volume of 0.375 per cent bupivacaine with epinephrine 1:200,000 up to four times a day for a maximum duration of seven days. Good pain relief was achieved in patients who underwent lateral and posterior thoracotomies. No pain relief was achieved in patients who underwent anterior thoracotomy or in patients in whom there was excessive bleeding in the pleural space. Bupivacaine blood concentrations were measured in 11 patients following the initial dose of 20 ml of 0.5 per cent bupivacaine (with epinephrine 1:200,000 in five of the 11 patients). The mean peak plasma concentration of bupivacaine when used with epinephrine was 0.32 +/- 0.02 microgram.ml-1. The mean peak plasma concentrations of bupivacaine when used without epinephrine was 1.28 +/- 0.48 microgram.ml-1. Our present data show that intrapleural analgesia is useful in the management of postoperative pain in patients who undergo thoracotomy. Our data also show that there is a significant decrease in peak plasma concentrations of bupivacaine when epinephrine is added to the solution (P less than 0.05).