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. So whether 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 blockade technique, 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 cytokines 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 can be evaluated as a more important marker of the status of Th1/Th2 type. And our results might provide some evidence about the molecular regulatory mechanisms in tumor cell development.