Background Although percutaneous coronary intervention (PCI) had become widely employed therapeutic procedure for coronary artery disease, stent restenosis limited the benefits of this revascularization and the question how to prevent such events remained unresolved. While numerous empirical observations suggested Tongguan Capsules ((sic)& x51a0;& x80f6;& x56ca;), a patented Chinese Medicine, could decrease frequency and duration of angina pectoris attacks, evidence supporting its efficacy on restenosis remained inadequate. Objective This trial was designed to determine whether Tongguan Capsules would reduce restenosis rate in patients after successful stent implantation. Methods Approximately 400 patients undergoing percutaneous coronary stent deployment were enrolled and randomized to control group or Tongguan Capsules (4.5 g/d) for 3 months. All patients received standard anti-platelet, anti-coagulation and lipid-decreasing treatments, concurrently. The primary clinical endpoint was the 12-month incidence of the major adverse cardiovascular events (defined as cardiac death, myocardial infarction, and recurrence of symptoms requiring additional revascularization). The angiographic end point was restenosis rate at 6 months. Conclusion This study would provide important evidence for the use of Tongguan Capsules in patients after stent implantation in combination with routine therapies, which may significantly reduce incidence of the restenosis so as to potentially improve the clinical outcomes. (registration number: ChiCTR-TRC- ChiCTR-IIR-17011407)