Abnormally elevated activity of ornithine decarboxylase (ODC), and subsequent polyamine accumulation are intimately associated with the genesis, development and metastasis of cancer, in the present study, to control the growth of tumor cells, ODC antisense RNA was used to transfect human lung squamous carcinoma cell line LTEP-78. Compared with the parental cells, growth of the antisense transfected LTEP-78 cells arrested in G0/GI phase and colony formation in soft agarose and tumorigenicity in nude mice were significantly reduced. Nucleic acid hybridization demonstrated that the transfectants expressed a high level of ODC antisense RNA and a significantly reduced level of endogenous ODC mRNA. The results suggest that the reversion of malignant phenolypes of human lung squamous carcinoma cells transfected with ODC antisense RNA is associated with the inhibition of polyamine biosynthesis.