Objective：To explore the distribution of absolute natural killer(NK) cell count in peripheral blood in patients with chronic lymphocytic leukemia(CLL)，and evaluate correlation with other clinical indicators and its prognostic value. Methods：The information of a total of 126 patients with CLL treated in the First Affiliated Hospital of NJMU from 2005 to 2014 were collected in this retrospective study. Comparisons of NK cell count as continuous parameter in different groups were described using Mann-Whitney U test and the Kruskal-Wallis test. Kaplan-Meier method was used to survival analysis，and the Cox proportional hazards models were used for the estimation of prognostic factors. Result：The median absolute NK cell counts were 0.54×109/L(range：0.01×109～4.11×109/L) in all the 126 CLL cases. The most discriminative cut-points of NK cell counts at diagnosis was defined as 0.20×109/L. With a median follow-up of 44.5 months，patients with NK cell count ≥0.20×109/L had a 5-year overall survival(OS) of 71.9%，whereas patients with NK cell count＜0.20×109/L had a 5-year OS of 48.4%(P=0.031). Univariate analysis showed that low NK cell count was associated with inferior OS(P=0.019)，and multivariate analysis confirmed NK cell count as an independent risk factor(P=0.005). Conclusion：Absolute NK cell count in peripheral blood of CLL patients may reflect level of immunity，the reduction of NK cell count indicate poor prognosis.