OBJECTIVE To study the antitumor effect of the stings of Gleditsia sinensis on mice bearing uterine cervical carcinoma (U14) and the expression of PCNA (proliferating cell nuclear antigen) and p53. METHOD The effect of the ethanolic extract of G. sinensis stings on the inhibition rate of solid tumor and the life span of ascites tumor were calculated by the animal tumor model experiment in vivo. The positive cell numbers of PCNA and mutant p53 protein were measured by immunohistochemical SP method. RESULT As compared with the control group, the ethanolic extract of G. sinensis stings (250, 500 and 1 000 mg x kg(-1) body weight, p.o.) and CTX (25 mg kg(-1) body weight, i.p.) administration significantly reduced the tumor weight of solid tumor and increased the life span of ascites tumor harboring mice (P < 0.01). The inhibition rate of solid tumor and the rate in life span were up to 47.44%, 59.49%, 63.92%, 73.42% and 52.21%, 67.26%, 78.76%, 95.58% respectively. Meanwhile,the expression of PCNA and mutant p53 protein also suppressed by ethanolic extract (P < 0.05, P < 0.01). CONCLUSION The stings of G. sinensis showed antitumor activity and its possible mechanism might be related with the expression inhibition of PCNA and mutant p53 protein.