Objective：To investigate the expression and value of P16INK4A, CDK4 and cyclin D1 protein in uterine smooth muscle tumors. Methods：The expression of P16INK4A, CDK4 and cyclin D1 protein in 21 cases of uterine leiomyosarcoma, 34 cases of uterine leiomyoma and 22 cases of normal myometrium was detected by SP immunohistochemical technique, and the expression of P16INK4A mRNA studied by in situ hybridization. Results：Positive rates of P16INK4A, CDK4 and cyclin D1 in uterine leiomyosarcoma, leiomyoma and normal myometrium were 62%, 90%, 57%; 15%, 26%, 53%; 10%, 10%, 0% respectively. There was significant difference in the expression of P16INK4A, CDK4（P ＜ 0.05） between leiomyosarcoma and leiomyoma.The expression of cyclin D1 showed significant different（P ＜ 0.05） between LMS and normal myometrium, LMA and normal myometrium. The in situ hybridization result and the immunohistochemical result is basic one. Conclusion：P16INK4A, CDK4 might play an important role in sarcomagenesis; Overexpression of cyclin D1 is a common molecular alteration that may occur in the early stage; Combining immunohistochemical detection of P16INK4A and CDK4 is helpful to distinguish leiomyosarcoma from leiomyoma.