Background: Appropriate postoperative pain management in shoulder surgeries is the mainstay of rehabilitation therapy and subsequent improved functional outcomes. However, adequate pain control either with opioids or interscalene brachial plexus block is often challenged by their side effects. In this context, this study compared the suprascapular nerve block (SSNB) to the newly emerging erector spinae plane block at the second thoracic vertebral level (high thoracic-ESPB) as an alternative pain therapy. Objectives: This study aimed to compare the efficacy of high thoracic-ESPB with SSNB as analgesic options for arthroscopic shoulder surgery. Study Design: Prospective randomized, double-blinded, controlled, clinical trial. Setting: This clinical trial was performed at Zagazig University. Methods: This prospective, randomized controlled clinical trial was registered at ClinicalTrials. gov (NCT04669639, December 15, 2020). Patient enrollment was initiated after the registration date (December 20, 2020), and the study was conducted from December 2020 to November 2021. Ninety-six adult patients who prepared for arthroscopic surgeries were assigned to the high thoracic-ESPB group, SSNB group, and control group; all with 32 patients each. Results: A significant difference was found between the control group and block groups concerning the Numeric Rating Scale (NRS-11) at recovery, 2, 4, 6, 8, and 12 hours postoperatively at rest and with shoulder movement. However, the NRS-11 was significantly higher in the SSNB group than in the high thoracic-ESPB group only with movement both at recovery and 2 hours postoperatively. Otherwise, no significant difference between the 2 block groups was found throughout different time points of the study. The doses of fentanyl given intraoperatively were significantly higher in the control group than in the high thoracic-ESPB and SSNB groups (mean ± standard deviation [SD], 326.6 ± 45.8, 224.7 ± 17.1, and 232.8 ± 17.8; P value < 0.001, respectively). A significant difference also was observed concerning postoperative morphine use, where the mean ± SD was 18.8 ± 2.9 in the control group vs 5.7 ± 1.02 and 6 ± 0.81 (P value < 0.001) in the high thoracic- ESPB and SSNB groups, respectively. Limitations: A continuous local anesthetic (LA) infusion catheter can be used either in the high thoracic-ESPB or SSNB to provide extended periods of analgesia. However, our investigation was confined to a single LA injection. Conclusions: SSNB is not inferior to high thoracic-ESPB in the context of phrenic nerve sparing pain control for arthroscopic surgeries. Moreover, SSNB is a more established technique with more predicted sensory distributions and a lower risk of LA toxicity.