1. Crotonoside is a bioactive ingredient from Croton Herba with a strong antitumour activity. This study aimed to develop a highly sensitive and selective high-performance liquid chromatography (HPLC) method to quantify crotonoside in biological samples for pharmacokinetics and distribution studies. 2. Protein precipitation by perchloric acid was used to separate crotonoside from the biological samples, and the recovery rates for crotonoside and the internal standard (luteoloside) were >80%. All calibration curves examining the crotonoside levels in plasma and tissues were linear (all correlation coefficients > 0.99). 3. The response to crotonoside appeared to be dose disproportional to the maximum plasma concentration and the area under the time-concentration curve in plasma over the range of 12.5-50.0 mg/kg, and crotonoside was highly distributed in tissues after intravenous administration. The highest crotonoside level was detected in the liver (28.79 ± 14.96 μg/g), whereas crotonoside was undetected in the brain.