Previous studies have shown that tumor cells predominantly express Th2 type cytokines and transcription factors.GATA-3,as a Th2-specific transcription factor,plays a central role in positive-regulating Th2 development.Sowhether the expression of GATA-3 in tumor cells has any effect on tumor development is a question of interest.In the present study,we inhibited the expression of GATA-3 in tumor cells through antisense RNA blockadetechnique,and observed its effects on tumor in vitro and in vivo.Our results showed that antisense GATA-3treatment could inhibit the expression of TNF-α and Th2 cytokiues in tumor cells,and antisense-induced blockadeof GATA-3 could also depress tumor growth in tumor-bearing mice.We suggest that the ratio of T-bet/GATA-3 canbe evaluated as a more important marker of the status of Th1/Th2 type.And our results might provide someevidence about the molecular regulatory mechanisms in tumor cell development.Cellular & Molecular Immunology.2005;2(3):189-196. Previous studies have shown that tumor cells predominantly express Th2 type cytokines and transcription factors. GATA-3, as a Th2-specific transcription factor, plays a central role in positive-regulating Th2 development. Howhether the expression of GATA-3 in tumor cells has any effect on tumor development is a question of interest. the present study, we inhibited the expression of GATA-3 in tumor cells through antisense RNA blockadetechnique, and observed its effects on tumor in vitro and in vivo .Our results showed that antisense GATA -3t treatment could inhibit the expression of TNF-α and Th2 cytokiues in tumor cells, and antisense-induced blockade of GATA-3 could also depress tumor growth in tumor-bearing mice. We suggest that the ratio of T-bet / GATA-3 canbe as as more important marker of the status of Th1 / Th2 type. And our results might provide some virity about the molecular regulatory mechanisms in tumor cell development. Cellular & Molecular Immunology. 2005; 2 (3): 189-196.