Objective:This study is aimed to investigate the value of absolute lymphocyte count (ALC) in predicting the clinical prognosis of patients with myelodyplastic syndrome(MDS).Methods:245 patients with MDS who diagnosed in our hospital from 2009 to 2019 were analyzed retrospectively, re-diagnosed according to WHO 2016 standard, and 208 patients with intact IPSS-R were risk-stratified, all of the patients′ peripheral blood ALC were collected and analyzed, through the time dependent receiver operating characteristic curve (ROC) analysis in Survival ROC package of R language, the optimal threshold value of ALC was 1.0×10 9/L. The patients of MDS were divided into normal ALC group (ALC ≥1.0×10 9/L) and low ALC group (ALC<1.0×10 9/L). Pearson χ 2 test and Mann-Whitney U test was used to analyze the differences in general data between the two groups. The overall survival (OS) curve and leukemia-free survival (LFS) were plotted by Kaplan-Meier method and compared by Long-rank test. Factors influencing the prognosis of MDS were analyzed by Cox Regression Model. Results:There were 97 cases in low ALC group and 148 cases in normal ALC group. The low ALC group had lower OS (15 months vs 60 months, P<0.000 1) and higher IPSS-R score (5.0 vs 3.75, P = 0.001). Multivariate analysis showed that ALC (<1.0×10 9/L) (HR:0.374,95% CI:0.153-0.917, P = 0.032) was independent risk factor of OS in IPSS-R-intermediate-risk MDS patients. Conclusion:This study shows that ALC in peripheral blood is an independent risk factor in IPSS-R-intermediate-risk MDS patients, which provides clinical evidence for the influence of body immunity on the development of MDS.