Thirty patients without any prior chemotherapy and histologically proved non-oat-cell advanced lung cancer entered a randomized trial comparing a combination chemotherapeutic regimen (cyclophosphamide, methotrexate, BCNU) and the same combination plus intradermic BCG. Twenty-nine patients were evaluable for survival. Mean survival was 11 and 3.5 months for chemotherapy and chemoimmunotherapy group, respectively. The difference was statistically significant (P less than 0.025). A tumor enhancement can be postulated. Skin tests before treatment (PPD, Candida, Varidase) seem to be prognostic for survival.