BACKGROUND: An explicit process of collaborative (shared) decision making involving the patient and physician has been recommended for discretionary surgical procedures in which small-area analysis demonstrates high variation not attributable to differences in the patient population in the area. One such example is laminectomy for lumbar herniated disk (HD). An observational study was undertaken to evaluate the impact of an HD videodisk program on patient satisfaction, decision making, and treatment preferences. METHODS: Enrollment occurred in the outpatient offices of surgeons treating Kaiser Permanente (Colorado Region) patients with HD who had indications for surgery. Enrollment took place from May 1993 to December 1995, and follow-up surveys of patients were completed by January 1997. RESULTS: A 6.0% decrease in the undecided group and a 1.3% decrease in the group preferring nonsurgical treatment drove a shift of patients toward laminectomy, from 26.7% to 35.8% (Wilcoxon signed rank test = 349.5, p = .017). Postviewing preference (74.0%) was a better aggregate predictor of the ultimate treatment than previewing preference (70.0%) for laminectomy. DISCUSSION: Viewing the videodisk increased the preference for laminectomy. However, limitations in the data prevented us from determining whether this change in preference was actually reflected in patients’ ultimate decisions. The fact that the strongest predictor of choosing surgery was the patient’s valuation of his or her condition supports shared decision making, with its emphasis on patient’s values. Participation in other videodisk programs has been low; perhaps physicians should ask patients to view these videodisks before their visits.