Electronic health records (EHRs) hold great promise for improving patient safety, but remain underutilized, especially in ambulatory care settings. Failure to appropriately follow up on abnormal test results is a common ambulatory care safety problem, and has been implicated in malpractice lawsuits arising from missed or delayed diagnoses. In this study conducted at eight family medicine clinics, those with an EHR documented clinician and patient notification of abnormal test results and clear follow-up plans more often than those with paper charts. However, even in clinics using EHRs, more than one-third of abnormal results had no follow-up plan documented. This finding corroborates prior research that clinician notification alone does not ensure timely and complete follow-up of test results.