To assess the efficacy of Tongxinluo capsule (TXLC) in treating variant angina pectoris and its effect on endothelial function.Sixty-four patients with variant angina pectoris were enrolled in the study for four weeks by a randomized clinical trial treatment with TXLC or isosorbide mononitrate.(1) The symptoms of both groups were significantly improved, the total effective rate of TXLC and isosorbide were 86.67% and 87.10% respectively; (2) The level of serum nitric oxide was increased, and the serum endothelin was decreased after treatment, there was no significant difference between these two groups.TXLC could effectively improve the symptoms of variant angina pectoris, the mechanism of which may likely be mediated by nitric oxide and endothelin.