Abstract: Objective To study the effect of FK506 in promoting apoptosis of peripheral blood-derived macrophages activated by homogenate of allogenic nerve tissues. Methods Homogenate of the allogenic nerve tissues was prepared using the sciatic nerve and injected in one-month-old SD rats, from which the macrophages activated by the homogenate were collected from the abdominal cavity and cultured in vitro. The cells were divided into 4 groups according to different concentrations of FK506 for treatment, namely 0 (group A, control group), 0.25 ng/ml (group B), 0.5 ng/ml (group C), and 1.0 ng/ml (group D). The cells of the 4 groups were inoculated into 96-well plate respectively for detecting the viability of the macrophages by MTT assay and for morphological evaluation of the cell apoptosis by transmission electron microscopy and fluorescence microscopy. Results The cells in groups B and C exhibited reduced viability and signs of apoptosis, and necrosis was observed in group D. Transmission electron microscopy and fluorescence microscopy identified early apoptotic changes and the presence of apoptotic body in the macrophages. The apoptotic rates of groups B and C were much higher than that in group A found by flow cytometry. Conclusion FK506 can promote the apoptosis of macrophage activated by allogenic nerve homogenate and reduce macrophage-mediated immunological rejection of peripheral nerve allograft.