Previous research suggests that patient education programs promoting shared decision making (SDM) may improve patient satisfaction and outcomes, yet controlled clinical trials are lacking. The authors evaluate the impact of an early breast cancer treatment educational video on patients' decisional preferences and behavior. Newly diagnosed stage I/stage II breast cancer patients were assigned to SDM video program or control groups in alternating months. Surveys were administered prior to the provider visit and 1 week following the treatment decision. Variables assessed included autonomy preferences, perceived involvement in care, satisfaction, and treatment choice. There were no significant intervention effects on informational/decisional preferences, anxiety, knowledge, or satisfaction. Although 25% of SDM patients chose mastectomy compared to 14% of controls, this difference was not statistically significant. Eventhough enthusiasm for SDM programs remains high among some patients and providers, this study found only modest benefits.