Prompt completion of diagnostic tests or referrals is paramount to receiving a timely diagnosis and treatment. In this study, completion rates for three common diagnostic tests or referrals (i.e., colonoscopy, concerning skin lesions, cardiac stress test) were compared between patients who do not access a patient portal; patients who do have access but do not read visit notes; and patients who have access and who do read visit notes. Completion rates were highest for patients who read visit notes (62%) compared with those who do not read notes (57%) and those with no portal use (54%). The authors state timely completion rates for all groups remain below recommend thresholds and increased patient engagement is required.