Communication breakdowns between surgical residents and attending physicians in the pre- and postoperative setting are common contributors to patient injury. These communication transactions might offer an opportunity for safety improvement, but it remains unknown how often resident-attending communication fails, what the current level of attending involvement is, and how often attending input changes the plan for patient care. We conducted a prospective study at 4 Harvard teaching hospitals to address these issues. Three prospective data collection strategies were employed: (1) we randomly selected surgical services and queried residents for the occurrence of predefined critical patient events and the characteristics of attending communications that ensued, (2) on weekends, randomly selected patients were interviewed and their charts reviewed to identify the frequency of attending visitation and how such visits affected processes of care, and (3) on weekends, senior residents on randomly selected surgical services were queried regarding the occurrence of attending-resident discussion of patients in their care. Of 80 critical patient events identified, 26 (33%) were not communicated to attending surgeons. Residents reported that, when contacted, all attending physicians were receptive to communication, whether they were the primary surgeon or providing cross-coverage. Although residents felt that attending contact was unnecessary for safe patient care in 61 (76%) of these events, discussions with attending physicians changed management in 33% (18/54) of cases in which they occurred. Attending surgeons were found to visit their patients on randomly selected weekend days 42% (n = 37) of the time, while 21% (n = 19) had not visited for 2 or greater days. When attending physicians visited patients, however, resident management was modified 46% (n = 36) of the time. Though residents frequently discussed patient management with attending physicians on randomly selected weekends, they failed to do so 16% (n = 58) of the time, which appeared to be related to service-specific variation (chi = 269, P < 0.0001). In the context of both critical patient events and routine patient care, residents often fail to obtain attending surgeons' input for management decisions. These failures seem to derive more from residents' perception of necessity than from attending physicians' receptiveness or interest in being contacted. Once involved, attending physicians frequently modify resident's management decisions. It seems, therefore, that there is significant potential for communication failure and information loss among our 4 institutions.