Attempts to improve survival following curative surgery for non-small-cell lung cancer are reviewed. Most of these approaches have been designed to stimulate the resistance of lung cancer patients in a non-specific fashion. Living bacteria or products of dead bacteria have been given as adjunctive treatment. Various routes have been used; oral, intradermal, subdermal, or intrapleural, with either BCG or Corynebacterium parvum. No reproducible benefit has been observed. Levamisole has not been proven to be useful. Trials have yet to be completed to confirm the use of thymosin fraction V for small cell carcinoma in improving the effectiveness of chemotherapy. A pilot trial using specific active immunotherapy is described. Prolongation of survival four years after closure of the trial in those patients immunized, compared with non-immunized patients, has prompted two further clinical trials. A small trial has confirmed the effectiveness of specific immunotherapy as adjunctive therapy for squamous cell carcinoma. A large multicenter trial in Canada and the United States should be completed and open to analysis in 1984 and may shed light on the role of tumor-associated antigens in stimulating specific resistance to lung cancer.