Abstract: ObjectiveTo evaluate the inhibitory effect of Nimesulide on tumor growth of human laryngeal squamous carcinoma in nude mice and to explore the possible mechanism involved in the inhibition. MethodsNude mice model bearing human laryngeal squamous carcinoma cell line(Hep-2)was established. The volumes of the subcutaneous tumor were observed after Nimesulide treatment. The levels of COX-2, CD44 and MMP-7 protein and mRNA in transplantation tumor were examined by immunohistochemistry and RT-PCR, respectively. ResultsThe growth of the carcinoma transplanted was significantly inhibited in the treatment group. Compared with the control group, the Nimesulide treatment group had significantly reduced weight and volume of tumor (all P＜0.05). There was no significantly difference in weights of mice increasing between the two groups. The levels of COX-2, CD44 and MMP-7 protein and mRNA of the treatment group were lower than those of the control group (all P＜0.05 ). ConclusionNIM has obvious inhibitory effect on the growth of human laryngeal squamous cell carcinoma Hep-2 cell xenografts in nude mice, through the down-regulation COX-2, CD44 and MMP-7.