Objective To observe the anti-HIV effects of Eucommia ulmoides Oliv,so as to provide experimental basis for searching a new efficacious drug for treatment of AIDS. Methods Using phytochemistry to isolate compounds from Eucommia ulmoides Oliv, MT4 cell infected by HIV as experimental model, and cell fusion as the activity-evaluating marker. Results Six compounds were isolated from Eucommia ulmoides Oliv. It and four of its compounds, (caffeic acid, (+) -catechin, chlorogenic acid, (-)epicatechin, especi...