Lack of timely follow-up of test results is an ongoing patient safety problem in primary care and can lead to missed or delayed diagnoses. This systematic review concluded that follow-up of abnormal mammograms in primary care is suboptimal. Findings from included studies indicate that ethnic minorities and women with lower educational attainment were more likely to have inadequate follow-up. Factors influencing follow-up include physician-patient miscommunication, alert fatigue, difficulty obtaining test results or patient records, and logistical barriers. The authors suggest adopting interventions focused on mitigating factors that negatively impact follow-up, such as patient navigation and case management.