OBJECTIVE To develop an assay for the determination of ferulic acid in rat serum.METHODS The content of ferulic acid in serum after oral administration of Shuguan liquid extract was determined by HPLC.ODS C₁₈column was used,the mobile phase was consisted of a mixture of methanol,1% acetic acid (35∶65 v/v).The detection wavelength was at 313 nm. RESULTS A linearity was obtained over the concentrations of 40～200μg·L^-1(r=0.9998,The linear regression equation Y=5.15×10^-6X+0.5824). CONCLUSION The determination method of ferulic acid in serum with organic solvent extraction was simple and accurate.