['Adherence to prophylactic antibiotics guidelines is challenging and poorly documented. We hypothesized that a multiphase, multifaceted quality improvement initiative would engage relevant stakeholders, address known barriers to adoption, and improve overall adherence.', "From 2011 to 2014, a series of interventions were introduced in the pediatric operating rooms. After each interventional period, prospective assessments were performed to record the antibiotic type, dose, timing, and redosing according to the guidelines. Perioperative factors that may influence guideline adherence were analyzed. Spearman's rank correlation, analysis of variance, and χ(2) tests were performed.", 'A total of 1,052 operations were observed, and 629 (60%) required prophylactic antibiotics. Adherence to all 4 guideline components remained unchanged (54-55%, P = .38). Redosing significantly improved (7-53%, P = .02), but correct type decreased (98-70%, P < .01). The percentage of cases in which only one antibiotic guideline component was missed remained unchanged (35-34%, P = .46). Adherence to guidelines was not significantly associated with American Society of Anesthesiologists class, surgical specialty, patient weight, anesthesia provider, or surgical wound class.'] Does adherence to surgical antibiotic prophylaxis remain a challenge despite multifaceted interventions?