The present study was designed to validate an analytical method based on HPLC for the quantitative measurement of the Apigenin-7-O-${eta}$-D-glucoside (AGL) in rat plasma after intravenous administration. HPLC analysis was done using a $C_{18}$ column, UV detection at 335 nm, and a mobile phase of methanol:0.2% phosphoric acid (1:1, v/v). Good linearity was observed over the range of $0.06-7.20{mu}g/mL$ with a lower limit of quantication of $0.06{mu}g/mL$. The intra-and inter-day precision values were below 9.97%. No interference peaks or matrix effects were observed. The method was fully validated and successfully applied to a pharmacokinetic study of AGL.