Therapeutic effect of short-term administration of IFN-a on non-small cell lung cancer ( NSCLC) was observed . Seventy-two cases of NSCLC patients were randomized into two equal groups. The control and the IFN-a group received the same chemotherapeutic treatments while the latter group were also intramuscularly injected with IFN-? 1 ? 10~(6)U/day for 20 days. Treatment effect rate, the number of white blood cells, the growth of carcinoma cells and the in-terclude time of chemotherapy were studied. Statistically significant difference with each index was observed between the two groups. The results indicated that the short-term administration of IFN-? during chemotherapeutic suppression inhibited tumor growth and made a shortened chemotherapeutic treatment interval acceptable. All showed that administration of IFN-? was feasible and effective in NSCLC chemotherapeutic treatment.