Objective To study the protective effects of bone marrow mesenchymal stem cells (BMSCs) of rhesus monkeys on porcine islets from hypoxia/reoxygenation (H/R)-induced injury. Methods BMSCs were isolated and cultured from the marrow of 5 adult rhesus monkeys (weighing, 6-10 kg) by adherent monocytes. Islets were isolated and purified from the pancreas of 5 neonatal porcine (3-5 days old) by collagenase V digestion method, and were cultured with or without BMSCs, and exposed to hypoxia (1%O2) for 12 hours and reoxygenation for 24 or 48 hours, respectively. The experiment was divided into 4 groups: normal islet group (group A), normal islet + BMSCs group (Group B), H/R islet group (group C), and H/R islet + BMSCs group (group D). The survival rate of islets was calculated by fluorescein diacetate/propidium iodide (PI) staining. The viability of the islet cells was detected by cell counting kit 8. Apoptotic rate of islet cells was tested using Annexin V-FITC/PI labeling and flow cytometry. The stimulation index (SI) of islet function was analyzed by glucose-stimulated insulin secretion assay. Results The islet cell cluster of group C was more dispersed than that of groups A and B, and group C had more death cells; and the islet cell cluster of group D was more complete and the survival rate was higher than those of group C. The survival rate of islet was 90.2% ± 9.1%, 88.3% ± 5.9%, 52.3% ± 12.1%, and 71.4% ± 11.5% in groups A, B, C, and D respectively, it was significantly lower in groups C and D than in groups A and B (P lt; 0.05), but it was significantly higher in group D than in group C (P lt; 0.05). After coculture of BMSCs and islet at the ratio of 1 ∶ 10 and 1 ∶ 20 in group D, the viability of islet cells was significantly higher than that in group C (P lt; 0.05). The apoptotic rate was 27.1% ± 3.2%, 24.0% ± 1.0%, 64.3% ± 1.8%, and 46.2% ± 1.4% in groups A, B, C, and D respectively, it was significantly higher in groups C and D than that in groups A and B (P lt; 0.05), but it was significantly lower in group D than in group C (P lt; 0.05). There was no significant difference in SI between groups A and B at each time point (P gt; 0.05), but it was significantly lower in group C than in groups A and B (P lt; 0.05); and it was significantly higher in group D than in group C at 24 and 72 hours (P lt; 0.05). Conclusion BMSCs of rhesus monkeys can protect islet vitality and function from H/R-induced injury.