Objective To investigate the effects of different dialysates on expression of protein kinase C-δ (PKCδ) and apoptosis of U937 cell line. Methods Different dialysates were added into culture fluid with U937 cell line at exponential phase of growth, and groups were divided: fluid A+fluid B group (dialysate A+dialysate B), fluid A+fluid B+rottlerin (PKCδ specific inhibitor)group, fluid A+powder B group (dialysate A+powder B) and fluid A+powder B + rottlerin group. Besides, blank control group and normal control group were established. Cells were harvested 24 h and 48 h after treatment, morphological changes were observed by Hoechst33258 fluorescence staining, cell apoptosis was measured by Annexin-V-FITC/PI double staining, and expression of PKCδ mRNA and protein was detected by RT-PCR and Western blotting, respectively. Results Cell apoptosis significantly increased in fluid A+powder B group, with typical morphology of apoptosis. After treatment for 24 h and 48 h, cell apoptosis rates in fluid A+powder B group were significantly higher than those at corresponding time points in blank control group , normal control group and fluid A+powder B+rottlerin group (P<0.05). Compared with normal control group, blank control group and fluid A+powder B+rottlerin group, the expression of PKCδ mRNA and protein of U937 cells in fluid A+powder B group were significantly increased (P<0.05). There was no significant difference in cell apoptosis rates and expression of PKCδ mRNA and protein between fluid A+fluid B group and blank control group, normal control group and fluid A+fluid B+rottlerin group (P＞0.05). Conclusion Fluid A+powder B can significantly increase apoptosis of U937 cell line, the mechanism of which may be associated with the up-regulation of expression of PKCδ. Compared with fluid A+powder B, fluid A+fluid B is superior in reducing apoptosis of peripheral blood monouclear cells.