A pilot study of electrochemical treatment (ECT) as a therapy for 386 patients with nonsmall cell lung cancer was undertaken. There were 103 stage II cases, 89 stage IIIa cases, 122 stage IIIb cases, and 72 stage IV cases. Two ECT methods were used: For peripherally located lung cancer, platinum electrodes were inserted transcutaneously into the tumor under x-ray or CT guidance. For central type lung cancer or for those inoperable during thoracotomy, electrodes were inserted intraoperatively directly into the cancer. Voltage was 6 -8 V, current was 40 -100 mA, and electric charge was 100 coulombs per cm of tumor diameter. The number of electrodes was determined from the size of cancer mass, because the diameter of effective area around each electrode is approximately 3 cm. The short-term (6 months after ECT) results of the 386 lung cancer cases were: complete response (CR), 25.6% (99/386); partial response (PR), 46.4% (179/386); no change (NC), 15.3% (59/386); and progressive disease (PD), 12.7% (49/386). The total effective rate (CR / PR) was 72% (278/ 386). The 1, 3, and 5 year overall survival rates were 86.3% (333/386), 58.8% (227/386), and 29.5% (114/386), respectively. The main complication was traumatic pneumothorax, with an incidence rate of 14.8% (57/386). These clinical results show that ECT is simple, safe, effective, and minimally traumatic. ECT provides an alternative method for treating lung cancers that are conventionally inoperable, that are not responsive to chemotherapy or radiotherapy, or that cannot be resected after thoracotomy. Long-term survival rates suggest that ECT warrants further investigation.