Objective To study the clinical significance of serum cystatin C (Cys C) in patients with acute leukemia (AL). Methods A total of 59 newly diagnosed AL patients in Xinghua City People's Hospital from January 2014 to August 2017 were enrolled; meanwhile, 59 healthy individuals who underwent physical examination at Medical Center of Xinghua City People's Hospital were selected as the control group. AU5800 automatic biochemical analyzer from American Beckman Coulter Corporation was applied to detect the levels of serum Cys C, lactate dehydrogenase (LDH) and creatinine (Cr). The receiver operating characteristic (ROC) curve was also drawn. Results The levels of serum Cys C and LDH in AL patients were higher than those in the control group [serum Cys C: (1.36±0.72) mg/L vs. (0.76±0.27) mg/L; LDH: (456±362) U/L vs. (185±29) U/L], and there was a statistical significance (t＝-5.965, P＝0.000; t＝-5.718, P＝0.000). There was no statistical difference in the serum Cr between AL patients and control group [(86±26) μmol/L vs. (82±16) μmol/L] (P＞ 0.05). There was a positive correlation between levels of serum Cys C and LDH in AL patients (rs＝ 0.447, P < 0.05). The ROC area under curve of serum Cys C was 0.823, the standard error was 0.037, and the confidence interval of 95 % was 0.751-0.896. The ROC area under curve of serum LDH was 0.811, the standard error was 0.042, and the confidence interval of 95 % was 0.728-0.894. Conclusion The level of serum Cys C in AL patients is higher than that in the healthy population. The detection of serum Cys C is helpful in the diagnosis of AL and the evaluation of tumor burden, which is consistent with serum LDH.