Delayed cancer diagnosis is a critical patient safety concern in primary care. Rectal bleeding is an important issue to recognize promptly, because it may be a symptom of colon cancer, for which delayed diagnosis can lead to worse outcomes. For this retrospective study, physician reviewers examined 438 abstracted medical records of patients with rectal bleeding to identify problems in the diagnostic process. In the majority of cases, they identified problems such as failure to elicit sufficient family history, incomplete physical examination performance or documentation, and lack of needed laboratory testing. Consistent with prior studies, failure to order laboratory testing and plan follow-up were associated with worse care quality. These findings emphasize the challenges of achieving timely and accurate diagnosis in the outpatient setting. In a related editorial, Hardeep Singh suggests that enhancing electronic health record capability and trigger tools could address diagnostic delays in primary care.