Strychnos camptoneura (Loganiaceae) is used in Congolese traditional medicine to treat variousdiseases such as malaria and diabetes, but not much is known about its effects on the immune system. Therefore, the purpose of this study was to investigate the immunomodulatory properties of S. camptoneura leaves. Mice were treated with the aqueous extract of S. camptoneura leaves (100 and 200 mg/kg); those administered with reverse osmosis water and β-1,3-glucan (150 mg/kg) were used as negative and positive controls, respectively. The immunomodulatory effects were measured 24 h posttreatment by quantifying the production of cytokines, and the number of myeloid and lymphoid cells. Treated mice with the aqueous extract showed a significant production of IL-4 and IL-10 compared to negative animals (P <0.001). Similar to β-1,3-glucan, both doses of aqueous extract markedly increased the number of macrophages, dendritic cells, CD4+ T and NK cells in treated-mice, but not of CD8+T cells. These findings suggest that the S. camptoneura leaves possess immunomodulatory properties. Further studies are needed to determine phytochemicals in these leaves and signaling pathways involved in the immunomodulation. This would help to better understand and valorize the therapeutic potential of S. camptoneura.