Background Failure to complete recommended diagnostic tests may increase the risk of diagnostic errors. Objectives The aim of this study is to develop and evaluate an electronic monitoring tool that notifies the responsible clinician of incomplete imaging tests for their ambulatory patients. Methods A results notification workflow engine was created at an academic medical center. It identified future appointments for imaging studies and notified the ordering physician of incomplete tests by secure email. To assess the impact of the intervention, the project team surveyed participating physicians and measured test completion rates within 90 days of the scheduled appointment. Analyses compared test completion rates among patients of intervention and usual care clinicians at baseline and follow-up. A multivariate logistic regression model was used to control for secular trends and differences between cohorts. Results A total of 725 patients of 16 intervention physicians had 1,016 delayed imaging studies; 2,023 patients of 42 usual care clinicians had 2,697 delayed studies. In the first month, physicians indicated in 23/30 cases that they were unaware of the missed test prior to notification. The 90-day test completion rate was lower in the usual care than intervention group in the 6-month baseline period (18.8 vs. 22.1%, p = 0.119). During the 12-month follow-up period, there was a significant improvement favoring the intervention group (20.9 vs. 25.5%, p = 0.027). The change was driven by improved completion rates among patients referred for mammography (21.0 vs. 30.1%, p = 0.003). Multivariate analyses showed no significant impact of the intervention. Conclusion There was a temporal association between email alerts to physicians about missed imaging tests and improved test completion at 90 days, although baseline differences in intervention and usual care groups limited the ability to draw definitive conclusions. Research is needed to understand the potential benefits and limitations of missed test notifications to reduce the risk of delayed diagnoses, particularly in vulnerable patient populations.