Objective To study the effect of repeated rectal exposure of low-dose simian immunodeficiency virus on the systemic cellular immunity in monkeys. Methods Eight 3- to 4-year old rhesus macaques (Macaca mulatta) (male:female 1:1) were used in this study. The monkeys were inoculated with 10 TCID₅₀ SIVmac239 virus through rectum twice a week for consecutive 6 weeks to establish a multiple rectal exposure model of SIVmac239 virus infection. Then, plasma viral load, CD4⁺ T cell count, T cell subsets and IFN-γ secretion of the experiment monkeys were determined. Results Low-dose SIVmac239 virus induced some changes in the immune system through the rectal mucosa, but didn't induce typical infection. Repeated rectal mucosal low-dose virus exposure can activate the cellular immune system. Conclusions This study defines the effect of repeated low-dose simian immunodeficiency virus exposure on the systemic cellular immunity, and provided basic information for HIV-1 vaccine research.