Objective:To compare the efficacy of superior trunk block (STB) versus interscalene brachial plexus block (ISB) in the patients undergoing arthroscopic shoulder surgery with general anesthesia.Methods:Sixty American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients, aged 18-70 yr, undergoing elective arthroscopic shoulder surgery, were divided into 2 groups ( n=30 each) using a random number table method: ISB plus general anesthesia group (group IG) and STB plus general anesthesia group (group SG). In group IG and group SG, 0.375% ropiacaine 15 ml was injected around C 5-C 6 nerve roots and superior trunk, respectively.SpO 2, diaphragmatic excursion, diaphragmatic paralysis, dyspnea and Horner syndrome were recorded at 30 min after injection.General anesthesia with tracheal intubation was then performed in all the patients, and remifentanil or phenylephrine was used to maintain hemodynamics stable.The use of remifentanil was recorded at the end of operation, the visual analogue scale score was performed after patients regained consciousness, and the duration of sensory and motor blockade was recorded at 24 h after operation. Results:Compared with group IG, the decrease in the amplitude of SpO 2 was significantly decreased, and diaphragmatic excursion was increased, the incidence and degree of diaphragmatic paralysis were decreased, duration of sensory blockade was prolonged, the incidence of Horner syndrome and dyspnea was decreased ( P<0.05), and no significant change was found in the requirement for remifentanil, postoperative visual analogue scale score, and duration of motor blockade in group SG ( P>0.05). Conclusion:STB not only provides better perioperative analgesia, but also reduces the incidence of diaphragmatic paralysis when compared with ISB in the patients undergoing arthroscopic shoulder surgery with general anesthesia.