Background: We have noted a high incidence of vasovagal episodes associated with use of interscalene block(ISB) for shoulder arthroscopy in the sitting position. The purpose of this retrospective study is to alert the possibility of potentially dangerous vasovagal events, describe the characteristics of this problem, and propose therapeutic devices. Methods: Results 62 patients who underwent shoulder arthroscopy in the sitting position with ISB were retrospectively analyzed. Group 1, 10 patients experienced vasovagal events characterized by sudden hypotension and bradycardia. Remaining 52 patients, Group 2, did not experience these symptoms. All patient charts were reviewed for age, sex, side of surgery, premedication, preoperative fluid and intraoperative medications. Perioperative hemodynamic changes were also compared between the two groups. Results: Vasovagal events experienced in 16% of patients(10/62) and occurred $39{pm}18$ min after sitting position and $22{pm}18$ min after start of operation. Number of patients who receiving anticholinergics for premedication were significantly lower in Group 1 than Group 2(2/10 vs. 28/52, p<0.05). Conclusions: Bezold-parish reflex is a potential mechanism for sudden hypotension and bradycardia which can occur during shoulder arthroscopy in sitting position. Therefore anticholinergic pretreatment and meticulous monitoring during operation are recommended to prevent B-J reflex.