Objectives: To assess the consequences of physician delay in the diagnosis of breast cancer by comparing stage, treatment, and outcome of patients with and without delay, and to identify patient characteristics that may make diagnosis more difficult. Summary Background Information: Delay in diagnosis of breast cancer is the most common clinical scenario resulting in malpractice litigation. Methods: The records of 1014 patients were reviewed and the events preceding the diagnosis were reconstructed. Accurate assessment of the physician delay in diagnosis could be made for 606 patients, 51 (8%) with physician delay >3 months. Patients with delay were comparable to patients without delay in terms of age, height, weight, age at menarche, pregnancies, children, proportion in menopause, age at menopause, and family history of breast cancer. Results: Thirty-six percent of patients who had a delay in diagnosis had normal mammograms versus 7% of patients without delay. Cancers in patients with delay were significantly larger on average than in those without delay, but there were no significant differences in pathology, differentiation, nodal status, TNM stage, treatment, or outcome. Conclusions: Physician delay in the diagnosis of breast cancer is common, and patients with delay are similar to patients without delay, although they are more likely to have normal mammograms. The consequences of physician delay in terms of stage at diagnosis, treatment, and outcome were not statistically significant.