Introduction: Effective physician-patient communication is critical in cancer care. Breakdowns in communication may follow an actual or suspected medical error because of various professional or medicolegal concerns about those events. We examined views of primary care physicians (PCPs) regarding two hypothetical medical errors, their perceptions of responsibility and intent to communicate these events to patients. Objectives: To describe PCPs views on medical errors, perceived responsibility and communication after errors during cancer care. Methods: We surveyed 630 PCPs at 3 healthcare organizations participating in the Cancer Research Network. Questionnaires included two vignettes describing possible medical errors: a delayed diagnosis of breast cancer and; preventable complications of colon cancer treatment. Questions assessed perceived responsibility and intent to communicate with the patient after the event. Results: A total of 333 PCPs responded (response rate =53%). Eighty-one percent felt that the delayed diagnosis vignette described a serious error; (60%) believed that the preventable complications of colon cancer treatment vignette represented a serious medical error. Few would offer no apology at all for the delayed diagnosis (4%) or the colon cancer complications complications (7%). The most common expression of regret was “I am sorry about what happened to you” without elaboration (48% delayed diagnosis; 56% complications). Just over half (51%) would not volunteer the cause of the delayed diagnosis; compared to 25% in the complications vignette. Perception of the error as serious, and of greater personal responsibility were both predictive of being more forthcoming when communicating to patient after the event; perceived self-efficacy in communication and the belief that one’s organization values good communication were not. Conclusion: PCPs vary in their attitudes towards medical errors, and their perceptions of responsibility. These attitudes and perceptions are predictive of how physicians intend to communicate with patients after such events, at least in response to two hypothetical cases.