AbstractA rapid and specific HPLC method for the simultaneous determination of gastrodin and its metabolite gastrodigenin (p‐hydroxybenzyl alcohol) in rat plasma, bile, liver, urine and faeces is described. The separation was achieved by using a reversed phase column (YWG‐C18) eluted with methanol‐water (2.5:97.5 v/v). Phloroglucinolum was used as internal standard and the peaks were detected at UV 221 nm. The protein precipitation with ethanol was a very simple and rapid method for sample preparation. The gastrodin and gastrodigenin were quantitated by measuring the peak‐height ratios. There was a linear concentration range of 10–320 μg/mL in the assay for both compounds. The coefficients of variation (within‐day) for samples spiked with gastrodin and gastrodigenin were 2.94% and 3.08%, respectively. The method demonstrated a high specificity and was suitable for use in pharmacokin