Objective: To study the effects of Ruanmailing Oral Liquid, a compound traditional Chinese herbal medicine, on spatial learning and memory ability and expression of apurinic/apyrimidinic endonuclease/redox factor-1 (APE/Ref-1) in hippocampal CA1 region in rats with experimental vascular dementia (VaD). Methods: VaD was induced in rats by permanent occlusion of bilateral common carotid arteries. Forty-five VaD rats were randomly divided into untreated group, nimodipine group, low-dose Ruanmailing group and high-dose Ruanmailing group. Another 15 rats underwent a sham operation consisting of similar skin incision and manipulation but without occlusion of carotid arteries. From the next day after occlusion, the rats were intragastrically administered with normal saline, nimodipine suspension or Ruanmailing Oral Liquid respectively for 30 days. Morris water maze experiment was adopted to test learning and memory of rats in each group. Expression of APE/Ref-1 protein in the hippocampal CA1 region was measured by immunohistochemical method. Results: Escape latency was significantly shortened and number of entries in the target area of rats was significantly increased in the high-dose Ruanmailing group as compared with those in the untreated group (P<0.01). Compared with the untreated group, count of APE/Ref-1 positive cells was significantly increased in the hippocampal CA1 region in the high- and low-dose Ruanmailing groups (P<0.01). Compared with the low-dose group and the nimodipine group, the count of APE/Ref-1 positive cells was remarkably increased in the hippocampal CA1 region in rats of the high-dose Ruanmailing group (P<0.01). There was no statistical difference between the low-dose Ruanmailing group and the nimodipine group. Conclusion: Ruanmailing Oral Liquid can improve the learning and memory ability and enhance the lowered expression level of APE/Ref-1 in the hippocampal CA1 region of rats with VaD.