Catalpol is an iridoid glycoside, distributed in the roots of Rehmannia glutinosa Libosch. In vitro results showed that preincubation with catalpol (0.5-0.5 mM) for 0.5 hours before and during 48 hour exposure to 0.2 mM MPP+ appeared to be significant protective effect while catalopl was considerably less effective at the doses of 0.001 to 0.01 mM. The addition of catalpol at the dose of 0.05-0.5 mM significantly increased DA and DOPAC to MPP+ treated group. C57bl/6 mice received administration of catalpol for 12 hours before and during the 7 day treatment with MPTP. Such treatment at doses of 15 mg/kg significantly and dramatically blocked tyrosine hydroxylase-positive cell loss in mice. DA turnover in MPTP mice was reversed in the nigrostriatal pathway. In conclusion, data obtained in the above study suggested that catalpol exerted neuroprotective action in vitro and in vivo PD model.