Ruminal impaction comprises 19.4% of cattle diseases in the Jiangsu province of China. The authors treated ruminal impaction in 55 cattle with electro-acupuncture (EA) of the classical acupoints Pi-shu and Du-jiao. Recovery occurred after 1 EA treatment in 40/55 (73%), 2 EA treatments in 9/50 (18%) and 3 EA treatments in 4/50 (8%) cattle. The final 2 animals recovered after 3 EA treatments and Chinese herbal medicine, Jian Pi Li Qi San. To determine the mechanisms of action of EA of Pi-shu and Du-jiao, 8 cattle with rumen impaction were randomly selected to compare rumen contractions, pH, fermentation and ciliate concentrations before and after EA. Compared to normal cattle, the frequency and duration of ruminal contractions greatly decreased, the pH increased and fermentation and number of ciliates decreased during ruminal impaction. After EA, contraction frequency and duration increased very significantly (p<0.001), the pH significantly decreased (p=0.02), the fermentation significantly increased (p=0.004) and the number of ciliates very significantly increased (p=0.0006). To investigate the effect of vagus nerve integrity on EA effectiveness, EA of Pi-shu and Du-jiao was performed on 8 clinically normal cattle and the frequency and duration of ruminal contractions increased. Following bilateral cervical vagectomy, ruminal contractions ceased and EA had no effect to restore ruminal movements. Based on the findings of this study and the successful treatment of 53 cattle with EA alone, it can be concluded that left unilateral EA of Pi-shu and Du-jiao provides an effective treatment for ruminal impaction.