While negotiation of treatment decisions in the medical visit has long been recognized as an important interviewing skill, limited work has been done to investigate how doctors and patients negotiate what information is relevant in understanding the patient's problem. In this research we tested how the introduction of information reflecting both the patient's and physician's perspective is related to the patient's adherence to physician recommendations for medication. Introduction of information was defined as bi-directional if patients independently offered information or behavior as frequently as they provided the information or exhibited behavior that physicians requested. Thirty random samples of audiotaped dialogue were used to construct estimates of introduction of information during the history, examination, and consultation phases of initial ambulatory care visits of 45 older male patients. The data demonstrate that bi-directional introduction of information during the examination segment explains more than half of the variance in patient adherence to physician recommendations for new medication. These findings support the idea that physician willingness to allow patients to contribute input may contribute to the partnership's arrival at treatment decisions that have meaning for both.