Background: Vascular dementia (VaD) is the second most prevalent type of dementia among the aged, for whom limited pharmacologic options are available so far. SaiLuoTong capsule is a modern traditional Chinese medicine formula, which has been demonstrated to improve cognition of VaDby the reports of animal experiments and preliminary clinical trial. However, evaluation of this therapy in randomized multicenter trials is needed. In this article, we present the rationale and design of the SaiLuoTong in Vascular Dementia Study. Methods: This phase 2 clinical trial of SaiLuoTong among patients with mild-to-moderate VaD is a 26-week, multicenter, randomized, double-blind, placebo-controlled study with a subsequent 26-week, open-label extension. After a 4-week placebo run-in period, participants are centrally randomized (1: 1: 1) to 3 groups: group A receives SaiLuoTong 360 mg per day for 52 weeks; group B receives SaiLuoTong 240 mg per day for 52 weeks; group C (the control group) are further randomly assigned to 2 groups in a 1: 1 ratio and receives placebo during the double-blind phase, then SaiLuoTong 360 mg per day or SaiLuoTong 240 mg per day during the extension phase. The primary outcome measures include the VaD assessment scale cognitive subscale and the Alzheimer Disease Cooperative Study-clinical global impression of change. Safety measures include body weight, vital signs, electrocardiography, laboratory tests, and records of adverse events. Assuming an attrition rate of 20%, at least 372 patients are required to obtain a statistical power of 80%. Results: The first patient was enrolled into the study in April 2012 and the completion of the study is expected in September 2014. Conclusions: The rigorous methodology of the study will hopefully move forward the scientific evaluation of traditional Chinese medicine in treatment of VaD. The results of the present study will provide high-quality evidence on the effect of SaiLuoTong in patients with VaD and has the potential to establish a novel therapeutic approach for this disorder.