To evaluate the frequency and nature of ethical disagreements over patient care between housestaff and attending physicians. During the spring of 1994, a cross-sectional survey about ethical disagreements was conducted of all 42 internal medicine housestaff at the West Virginia University Hospitals and all 51 faculty in the Department of Medicine at the West Virginia University School of Medicine. Chi-square analysis was used to compare categorical variables. Thirty-six (86%) of the residents and 41 (80%) of the faculty responded. The housestaff recounted 127 ethical disagreements between attending physicians and housestaff in the previous year; the attending physicians reported 19. A total of 32 residents reported at least one ethical disagreement with an attending physician during the previous year. When asked about their most troubling disagreement, 27 (84%) of these residents reported they had been distressed because they considered the treatment ordered by the attending physician to be futile. Only 11 residents (34%) had discussed their most troubling disagreement with the attending physician. Of the 24 residents who correctly identified that a formal process to resolve ethical disagreements with a physician did not exist, 17 desired one. The residents' disagreements with attending physicians over ethical aspects of patient care were common and usually concerned issues of overtreatment. Since most of the housestaff did not express their concerns, the attending physicians were largely unaware of them. The findings suggest that residency directors need to encourage housestaff to discuss their ethical conflicts with attending physicians.