The increased risk of developing age-related diseases in the elderly is associated with an imbalance and deficiency of the immune response, therefore, specific treatment and vaccination approaches should be developed. The efficiency of phagocytic activity is a significant organism's indicator which decreases with the aging of the immune system. The medications are able to influence phagocytosis, having a blocking or activating effect, are important modulators of immune function. We are developing an ex vivo assay indispensable for medication screening in human and Macaca fascicularis whole blood. M.fascicularis is the well-recognized preclinical model having human-like immune responses. This assay is suitable for routine phagocytosis quantification experiments, including distinguishing between particles adhering to the cell surface and ingested particles. For assay verification several published control drugs were successfully used for blocking and acceleration of phagocytosis. Besides, this test is combined with another activity type such as ROS assay and antibody staining. Ongoing experiments evaluating human and animal phagocytosis indices at different ages will provide statistical standards to be used for medication preclinical and clinical trials. This assay assists to find medications for enhancing the immune response and antigen presentation in the elderly. Moreover, screening of medications, having impact to phagocytosis and further researches of their mechanisms may bring us closer to the comprehension of fundamental process of immune system aging and to provide a perspective for immune response correction.