Background: Rotator cuff repair is a successful treatment in terms of patient satisfaction and pain relief regardless of the repair method. Although arthroscopic repair is commonly thought to be less painful than open or miniopen repair, studies disagree on this point. Questions/purposes: We wished to compare the results of patient-reported postoperative pain after open versus arthroscopic rotator cuff repair and to identify any predictors of various pain outcomes in these groups. Methods: One-hundred two patients (52 with open repair, 50 with arthroscopic repair) participated. Preoperatively, patients reported pain levels and self-perceived pain tolerance, and they underwent a test for an objective measurement of pain tolerance. Intraoperative variables included surgery duration and size of the tear. Postoperatively, patients maintained a pain log for 6 weeks, reporting daily pain (VAS) and narcotic consumption. Outcome variables included days to zero pain, the presence of residual pain, weekly pain levels, and cumulative 6-week pain level. Age, sex, tear size, pain tolerance, surgery duration, and self-reported preoperative pain were analyzed as possible predictors of postoperative pain. This study was powered (β = 0.2 and α = 0.05) to detect a difference of 10% in the VAS and postoperative analgesic use with a requirement of 50 patients in each arm. Results: Days to zero pain (mean, 28.8 days, 95% CI, 24.8-32.8 days versus 27.6 days, 95% CI, 23.3-31.9 days for open versus arthroscopic, respectively; p = 0.69) were not different between the open and arthroscopic repair groups. There were differences of questionable clinical relevance and borderline statistical significance favoring arthroscopic intervention in the second postoperative week (2.3 versus 3.2 of 10 on the VAS; p = 0.045). Otherwise, no differences were seen between the two groups in terms of residual pain, cumulative pain, or medication use. Consistent predictors of postoperative pain affecting multiple outcome measures included severe preoperative pain, smaller tear size, and female sex. Conclusions: There were no differences of clinically relevant size between arthroscopic and open rotator cuff surgery in this comparative series. Therefore, the choice of arthroscopic rotator cuff repair should not be based on decreased postoperative pain. Level of Evidence: Level II, therapeutic study. See the Instructions or Authors for a complete description of levels of evidence.