Objectives Lymphocytes can affect the proliferation and migration of muscle satellite cells, which may be associated with reduced muscle mass in patients with sarcopenia. The present study aimed to further enrich understandings of the changes of blood lymphocytes and explore the relationship between peripheral lymphocyte subsets and muscle mass in patients with sarcopenia. Design A cross-sectional study. Setting Geriatrics department of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. Methods Eighty-five subjects were enrolled in this study, and were divided into two groups: the sarcopenia group (n=60) and the non-sarcopenia group (n=25). The diagnosis of sarcopenia was based on the diagnostic criteria updated by the Asian Working Group for Sarcopenia (AWGS) in 2014. Complete blood count, peripheral lymphocyte subsets, and body composition of all patients were measured. Results Skeletal muscle mass index (SMI) was negatively correlated with CD4(+)CD28(null) T lymphocytes in peripheral blood in patients with sarcopenia. Conclusion The result of our study may point out the role of CD4+CD28(null) T lymphocytes in the pathogenesis of sarcopenia.