Objective:The purpose of this study was to investigate the anti-metastatic effects of nm23-hl gene on high pulmonary-metastatic adenoid cystic carcinoma cell line(ACC-M) .Methods: 20 BALB/C nude mice were randomly divided into two groups, and one group was injected with 5x10 nm23-hl positively-transfected cells via tail vein; The other group was injected with non-transfected cells as the control. One week after injection, 2 mice of each group were killed, 4 weeks after that the remaining mice were killed for gross and histological examination. Results: There was no obvious difference between the two groups 1 week after injection observed by naked eye examination. 4 weeks after the injection, there were lots of gray-white metastatic nodules on the surface of mice lung of the non-transfected group, while only a few metastatic nodules were found in the transfected group. The histological results accorded with the above visual observation. Conclusion: nm23-hl gene could inhibit the pulmonary metastasis of ACC-M. More