Wu L, et al. - In this retrospective analysis of Chinese Han population from Chaoshan region in South China, researchers sought to determine the reference range of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in these subjects. In this study with 5000 healthy adults (aged 20–69 years), 2500 were men and 2500 were women. Across all ages, the estimated mean NLR and PLR for men and women were 1.59 ± 0.59, 92.88 ± 28.70, 1.62 ± 0.64 and 108.02 ± 32.99, respectively. In normal male and female, the identified 95% reference range of NLR were 0.43~2.75 and 0.37~2.87 and that of PLR was 36.63~149.13 and 43.36~172.68, respectively. Females vs males exhibited a higher NLR at age 30~49. At age 60~69, males had higher NLR as compared to females. Females vs males exhibited a higher PLR. Overall, variations were evident in NLR and PLR by age and sex.