Abstract: The physiological disposition of ³H-gastrodin in female Sprague-Dawley rats was studied. The decline of radioactivity from gastrointestinal tract (GIT) was rapid following oral administration of ³H-gastrodin, and only 1.1% of the dose was recovered from the GIT after 8 hours. Rats were given intragastrically ³H-gastrodin, the radioactivity in blood was on a moderate level at 5 min and reached its peak at 50 min. Radioactivity was found to be highest in the kidney, moderate in liver, lung and womb, lower in the brain and reached maximum at 2 hours in the brain. The radioactivity excreted in urine, feces and bile within 24 hours was 66.1%, 0.63% and 3.06% respectively of the dose per os. The drug-plasma protein binding of ³H-gastrodin was found to be 4.3%, and that of its genin was 69.3%. The main metabolite detected by TLC was the genin (p-hydroxybenzyl alcohol).