Abstract: AIM: To observe the effect of bisoprolol, a β1-receptor blocker, on malignant ventricular arrhythmia (MVA) and heart rate turbulence (HRT) in patients with unstable angina pectoris (UAP). METHODS: Thirty-three UAP patients with premature ventricular beats were treated with bisoprolol for 30 days as treatment group and 25 patients were treated with placebo for the same period as control group. A 24-h ambulatory electrocardiogram monitoring was conducted before and after bisoprolol (5 mg/day) or placebo in all patients. The number of patients with MVA, turbulence onset (TO) and turbulence slope (TS) were analyzed in both groups. RESULTS: After the 30-day treatment of bisoprolol in patients with UAP, the number of patients with MVA decreased by 17.2%, TO decreased and TS increased. No significant changes were found in the control group. CONCLUSION: β1-receptor blocker, bisoprolol, reduces the incidence of MVA and improves HRT in patients with UAP.