We used a pain questionnaire to evaluate the prevalence and functional significance of long-term postthoracotomy pain. Data on 56 patients who were at least 2 months postsurgery were analyzed. Thirty patients (54 percent) with a median follow-up of 19.5 months had persistent pain; 26 others were pain free at a median of 30.5 months postthoracotomy. Pain was reported in 24 of 44 patients (55 percent) who were more than one year after surgery, 13 of 29 patients (45 percent) more than two years, six of 16 (38 percent) more than three years, and three of ten patients (30 percent) greater than four years postthoracotomy. Pain intensity was low, but 13 patients stated that pain "slightly" or "moderately" interfered with their lives. Five of 56 patients had sufficiently severe chronic pain to require either daily analgesic use, nerve blocks, relaxation therapy, acupuncture, or referral to a pain clinic. We conclude that long-term chest wall pain is common postthoracotomy. It is generally not severe, but a small proportion of patients may experience persistent, moderately disabling pain.