Background: Variations exist in compliance with NCCN Guidelines. Prior reports of adherence to NCCN Guidelines contain limitations because of lack of contemporary review and incomplete listing of reasons for noncompliance. Purpose: To assess institutional compliance and assist national quality improvement strategies through identifying valid reasons for noncompliance. Methods: Compliance with NCCN Guidelines was recorded prospectively using electronic synoptic templates for patients with newly diagnosed breast cancer treated at a single institution between January 2010 and December 2011. Compliance with NCCN Guidelines was recorded. The accuracy of real-time synoptic auditing methods compared with retrospective chart review and reasons for noncompliance was assessed. SAS 9.3 software was used for data analysis. Results: Compliance with NCCN Guidelines among 395 patients was 94% for initial staging evaluation, 97% for surgery, 91% for chemotherapy, 89% for hormone therapy, 91% for radiation therapy, 85% for follow-up, and 100% for determination of estrogen receptor/progesterone receptor and HER2 status. Age, comorbidities, and stage influenced guideline compliance. The most common reasons for noncompliance were patient refusal, patient choice after shared decision-making, and overuse of testing. Synoptic templated reporting was accurate in 97% patients. Conclusions: High compliance with NCCN Guidelines was demonstrated. Reasons for noncompliance were identifiable. Compliance and nonadherence can be evaluated quickly with electronic synoptic reporting. This allows real-time action plans to address quality concerns and aids national risk adjustment for comparison and benchmarking.