Objective To study the effect of SIVmac251-infection on apoptosis induction of macrophage from rhesus macaque by galectin-3. Methods Monocytes were isolated from peripheral blood of healthy or SIVmac251-infected rhesus macaques. Cells were induced to differentiate to macrophages by GM-CSF and IL-6. Macrophages were cultured for 5.5 hours at the presence of galectin-3. Cells were stained by PE-Annexin V/ PerCP-7ADD and apoptosis was examined upon flow cytometry. Results The percentages of Annexin V cells without galectin-3 induction were 5.08% and 4.87% for macrophages from healthy or SIVmac251-infected rhesus macaques respectively. The percentages of them with galectin-3 induction increased to 17.62% and 45.56% respectively. The increase for SIVmac251-infected rhesus macaque was significantly greater than that for healthy monkey (p﹤0.01). Conclusion SIVmac251-infection results in sensitivity enhancement to apoptosis induction of macrophage from rhesus macaque by galectin-3.