Results of several studies by the Lung Cancer Study Group have shown that postoperative adjuvant chemotherapy enhances survival following surgery for lung cancer. The 18-month disease-free survival almost doubled in one study using cyclophosphamide, doxorubicin, cisplatin (CAP) chemotherapy postoperatively. The recurrence rate remained significant, however. Patients with more advanced resectable disease seem to benefit most from postoperative chemotherapy. Results also suggest that CAP delays recurrences more effectively in patients with nonsquamous vs. squamous lung carcinoma. There has been considerable interest in the use of preoperative adjuvant therapy as well. Findings from studies of preoperative or induction therapy--either chemotherapy alone or in combination with radiation therapy--have shown high response rates and that patients with unresectable disease can be converted to technically resectable. Although preoperative therapy can cause difficulties with surgical dissection, surgical morbidity is acceptable. Preoperative chemotherapy and radiotherapy followed by surgical resection clearly eliminates local recurrence. Systemic recurrences remain a significant problem. The evidence, as yet, does not indicate that preoperative adjuvant therapy prolongs survival.