Electro-acupuncture (EA) is believed to be effective for alleviating motor symptoms in patients with Parkinson's disease. In a rat hemiparkinsonian model induced by unilateral transection of the medial forebrain bundle (MFB), the effects of EA stimulation were investigated. EA stimulation at a high frequency (100 Hz) significantly reduced apomorphine-induced rotational behavior. Tyrosine hydroxylase immunohistochemical staining revealed that EA at 100 Hz protected axotomized dopaminergic neurons from degeneration in the substantia nigra (SN). Moreover, high frequency EA reversed the axotomy-induced decrease in substance P content and increase in glutamate decarboxylase-67 (GAD 67) mRNA level in the midbrain; however, it did not affect the axotomy-induced increase in enkephalin content in the globus pallidus. These results suggest that the effects of high frequency EA on motor symptoms of Parkinsonian rats may involve restoration of the homeostasis of dopaminergic transmission in the basal ganglia circuit.