Out-of-pocket-costs incurred by patients for medical services have grown from $25.1 billion in 1970 to more than $205 billion in 2001. This study examines barriers preventing patient-physician communication about out-of-pocket expenses. Survey participants (patients and physicians) were asked to recall a time when they wanted to discuss these costs but did not do so. One hundred and thirty-three general internists and 484 of their patients from three academic and 18 community practices took part in the survey. Patients were considered burdened by out-of-pocket costs if they had not taken medication within the past 12 months as a cost-cutting strategy, or they had a problem paying their health care bills. Overall, 54 patients and 77 physicians recalled a specific time when they wanted to talk about out-of-pocket expenses but were unable to do so. Barriers identified by patients included discomfort discussing the topic (19%); insufficient time (13%); a belief that the physician would not have a solution to offer (11%); and concerns that the discussion might affect their quality of care (9%). Among physicians the most common barriers reported were insufficient time and a belief that they did not have a solution. Full-text of this journal article is available free-of-charge.