Abstract: AIMTo study whether the immunosuppressant tripchlorolide (T₄) exerts neuroprotective effect on dopaminergic neurons. METHODSA rat model of Parkinson's disease (PD) was set up by transection of the medial forebrain bundle (MFB) with a wire knife. The rotational behavior, HPLC-ECD, tyrosine hydroxylase (TH) immunocytochemistry, ELISA methods were used to evaluate the influence on the dopaminergic neurons following T₄ treatment. RESULTST₄ treatment was shown to effectively attenuate the rotational behavior challenged by amphetamine (2.5 mg·kg^-1, ip) in the PD rats. T₄ markedly prevented the decrease of dopamine content in the striatum and the loss of dopaminergic neurons in the substantia nigra pars compacta. T₄ was found to suppress the abnormal increase of TNF-α and IL-2 level in brain tissues of PD rats after MFB transection. CONCLUSIONThe evidence that the immunosuppressive Chinese herb extract T₄ possesses neuroprotective activities on the dopaminergic neurons in PD rats was presented. The underlying mechanism of T₄ may be relevant to its immunosuppressive activity.