OBJECTIVE: To explore the effects of simvastatin on T cell subsets and expression of inflammatory factors in peripheral blood of rats with rib fracture. METHODS: The rat rib fracture model was established（ n = 60）

and the rats were divided into the control group and low-dose and high-dose simvastatin group. X-ray in vivo imaging was used to detect bone healing. CD4

+

T lymphocytes and CD8

+

T lymphocytes in peripheral blood of rats were detected by flow cytometry

and CD4

+

/CD8

+

was calculated. Enzyme-linked immunosorbent assay was used to detect the changes of levels of tumor necrosis factor-α（ TNF-α） and interleukin 17（ IL-17） in the peripheral blood of rats.RESULTS: Compared with the control group

the bone healing degree of the low-dose and high-dose simvastatin group were better than those of the control group. The contents of CD4

+

T lymphocytes and CD8

+

T lymphocytes and the ratio of CD4

+

/CD8

+

in high-dose and low-dose simvastatin group were significantly higher than those in the control group at the 1 st and 2 nd week of administration

with statistically significant difference（ P

<

0. 05）. There was no significant difference between the low-dose simvastatin group and the high-dose simvastatin group（ P

>

0. 05）. At the 3 rd and 4 th week of administration

there was no significant difference in the content of CD4

+

T lymphocytes

CD8

+

T lymphocytes and the ratio of CD4

+

/CD8

+

in the peripheral blood of three groups of rats（ P

>

0. 05）. Compared with the control group

the levels of TNF-α and IL-17 in peripheral blood of rats in the low-dose and high-dose simvastatin group increased significantly at the 1 st and 2 nd week of administration

and the differences were statistically significant（ P

<

0. 01）. At the 3 rd and 4 th week of administration

there was no significant difference in the levels of TNF-α and IL-17 in the peripheral blood of three groups of rats（ P

>

0. 05）. CONCLUSIONS: Simvastatin can affect the balance of immune cells in the early stage of fracture in rats

increase the release of immune cytokines TNF-α and IL-17 in the early stage of fracture

and promote early bone healing.