Objective To investigate the in vitro destructive effect of chlorogenic acid (CRA)/isochlorogenic acid (IRC)on Aspergillus fumigatus biofilm in a model of biofilm formation.Methods The in vitro biofilm model was established using clinical isolates of A.fumigatus.The minimum inhibitory concentrations (MIC)of antimicrobial agents against A.fumigatus were determined by microdilution method.Scanning electron microscope (SEM)and laser confocal scanning microscope (CLSM)were used to characterize the biofilm.Crystal violet staining method was used for biofilm quantitation.Results After reaction with CRA/IRC for 24 h or 48 h,observation of biofilm showed that A.fumigatus extracellular matrix was thinner than the control group.Biofilm quantitation showed that the optical densities were 1.05±0.19,1.14±0.26,0.99±0.14 for CRA group (1 024 mg/L,512 mg/L,256 mg/L);1.39±0.06,1.41±0.06,1.60±0.04 for IRC group (1 000 mg/L,500 mg/L,250 mg/L)at 24 h,and 1.91±0.17 for control group (P<0.05).The quantitation of biofilm showed that the optical densities were 2.25±0.05,2.27±0.05,2.31±0.03 for CRA group,2.26 ± 0.02,2.27±0.02,2.29±0.04 for IRC group at 48 h,and 2.36±0.01 for control group (P<0.05).Conclusions CRA/IRC has some inhibitory effect on the formation of A.fumigatus biofilm.