Objectives: This study aims to evaluate the severity of postoperative pain and the time to the onset of pain after arthroscopic surgical treatment of rotator cuff tear or instability under interscalene block. Patients and methods: Between October 2015 and June 2016, a total of 172 patients (82 males, 90 females; mean age: 47.9±16.9 years; range, 15 to 83 years) who underwent shoulder arthroscopy under interscalene block by a single surgeon were retrospectively analyzed. The relationship between the postoperative 24-h Visual Analog Scale (VAS), the time to the onset of pain with the type of surgical procedure (rotator cuff repair, n=101 or instability surgery, n=71), and the duration of surgery (<30 min n=92; ≥30 min n=80) was examined. Results: No significant relationship was found between the type of surgical procedure, VAS scores, and the onset of pain after the block (p=0.577 and p=0.780, respectively). No significant relationship was found between the operation duration, and VAS, and the onset of pain after the block (p=0.570 and p=0.408, respectively). The mean duration until the start of postoperative pain was 734±313 (range, 60 to 1,440) min. There was no statistically significant difference in the need for rescue analgesics at the postoperative 24th h and the duration of surgery between the two groups (p=0.393 and p=0.675, respectively). Conclusion: Our study results show no significant difference in the time for the onset of postoperative pain and the VAS scores according to the characteristics of the surgical procedure, operation duration, or age and sex of the patient. Shoulder arthroscopy performed by experienced surgeons under interscalene block eliminates the need for analgesics within the first 12 h postoperatively.