Breast cancer (BC) patients experience multiple symptoms as a result of diagnosis and treatment. While surveillance for detecting cancer recurrence is fundamental to follow-up care, managing symptoms, and promoting health behaviors are equally important. UCSF has implemented a secure online health questionnaire enabling BC patients to provide updates of their health history and symptoms. We randomly selected a sample of stage I-III BC patients (n = 106) who completed a questionnaire before a medical oncology visit between August 2010 and January 2011 and consented to have data used for research. We conducted a chart review calculating the number of symptoms reported in the questionnaire, the clinic note only, and both questionnaire and clinic note, excluding chronic symptoms addressed previously. Self-reported data on exercise and alcohol consumption was compared to documentation of these lifestyle factors in clinic notes. Patients reported significantly more symptoms using the online questionnaire (mean = 3.8, range 0-13) than were documented by the provider in clinic notes (mean = 1.8, range 0-7; p < 0.001 for the difference). A regression plot comparing the percentage of symptoms agreed upon by the patient and provider and the percentage of symptoms addressed yields a slope of 0.56 (95 % CI 0.41-0.71). The number of self-reported symptoms correlates with self-reported Karnofsky scale such that the number of symptoms reported by the patient increases linearly with this score until a threshold and it then plateaus (p < 0.001). Exercise behavior and alcohol consumption were reported in 100 % of the online questionnaires, but was documented in only 30/106 (28 %) and 75/106 (70 %) of charts reviewed. In 19/75 (25 %) charts with alcohol consumption documented, there was substantial discordance between patient and clinician reporting. Electronic data collection of BC patient-reported outcomes has a positive effect on symptom management and identification of opportunities for risk-reducing behavior change.