Patients with cancer have been shown to face unique safety risks while receiving treatment, as their care requires coordination across multiple disciplines and the use of high-risk medications. This Swedish study looked at a previously unexamined aspect of safety—harm experienced by patients while undergoing the diagnostic workup for suspected cancer. The population-based analysis found that patients experienced an increased risk of adverse events during the 2 weeks prior to a diagnosis of cancer and for a short time afterward. It is likely that these adverse events are due in part to the invasive procedures required for diagnosis. Moreover, patients were more likely to experience other types of injuries as well, corroborating prior studies that have found that patients recently diagnosed with cancer are at elevated risk of suicide and accidental injury. Although diagnostic error has been an increasing focus of safety efforts, this study broadens the concept of diagnostic harm by analyzing adverse events associated with the diagnostic process itself.