Objective To investigate the effect of exosomes in the pathogenesis of ⅢA chronic prostatitis(CP). Methods A total of 30 patients with ⅢA CP in our hospital from April to August 2018 were selected as ⅢA group

and 14 healthy people were selected as control group.Differential ultracentrifugation was performed to isolate exosomes from the expressed prostatic secretion in urine(EPSurine).Exosomes were characterized by transmission electron microscopy and Western blot.The size of exosomes were analyzed by particulate size description analyser.Exosomes were quantified using Exosome Quantification Assay Kit（ExoELISAULTRA CD631）.Proteins were quantified by BCA assay. Results Exosomes were successfully isolated from EPSurine and identified by transmission electron microscopy and Western blot. The average size of exosomes in control group was (157.5±2.27)nm

that in ⅢA group was (155.4±1.73)nm

the difference was not significant（t=0.7，P>0.05）.The exosomes concentration in control group was (6.13±1.19)×1013/L

that in ⅢA group was (9.77±1.05)×1013/L

the difference was significant（t=2.09，P<0.05）.The protein concentration in control group was (1.24±0.16)g/L

that in ⅢA group was (1.84±0.17)g/L

the difference was significant（t=2.18，P<0.05）.Conclusion The level of exosomes in ⅢA group was significantly higher than that in control group.Exosomes may have an important role in the etiology of ⅢA CP.