80 patients scheduled for shoulder arthroscopy or arthroplasty were randomized to preoperative skin washing over the first 2 days before surgery and on the day of surgery consisting of either 5% benzoyl peroxide or 4% chlorhexidine gluconate. Patients had samples taken immediately after perioperative skin preparation from skin sites corresponding with anterior, lateral, and posterior arthroscopic portals, as well as the axilla. Samples were also taken from the nonoperative shoulder to act as a negative control. Samples were tested for Cutibacterium acnes (C. acnes) colony forming unit counts. Results demonstrated that reduction in C. acnes CFU count relative to the nonoperative shoulder was significantly greater at the anterior and posterior sites in the BPO group compared to the CHG group, while differences at the lateral and axilla sites were not significant. No case of postoperative infection or wound complication was noted in either group.