The aim of this work was to evaluate the lymphocyte immunophenotype in an elderly population. This study enrolled 35 over 60-year-old volunteers and a control group composed of 35 young adults. The study included elderly without diseases that might affect the functioning of the immune system. These individuals were consulted by doctors and after a physical examination, laboratory tests were performed using a Beckman Coulter(®) flow cytometer. The GraphPad Prism computer program was employed for statistical analysis with the level of significance being set for p-values <0.05. There is a statistically significant reduction in the number of lymphocytes (CD8(+), CD2(+) and CD3(+) cells) in the elderly compared to young adults. These low rates are explained by changes attributed to aging and may be partly responsible for the reduction in the cellular immune response, lower proliferative activity and the low cytotoxicity of lymphocytes. These parameters showed greater impairment of adaptive immunity in the elderly population and can therefore explain the greater fragility of the aged body to developing diseases.