While poor performance during a maximal graded exercise test (GXT) predicts cardiovascular events and premature mortality, the potential clinical importance of non-participation in a GXT, either for medical or non-medical reasons, is currently unknown. Data are from 4086 and 3547 Coronary Artery Risk Development in Young Adults (CARDIA) participants who attended the Year 7 (ages 25–37 years) and/or 20 exams (ages 38–50 years), respectively, which included a GXT. Cox proportional hazard models were used to examine the effect of GXT disposition (at Year 7 and 20, separately) on risk of non-fatal and fatal cardiovascular events and all-cause mortality obtained through 28 years of follow-up. A GXT was not conducted or completed according to protocol in 12.9% and 19.1% of participants attending the Year 7 and 20 exams, respectively. After adjustment, participants who missed the Year 20 GXT for medical reasons had a higher risk of cardiovascular events [HR: 4.06 (95% CI: 1.43, 11.5)] and all-cause mortality [HR: 3.07 (95% CI: 1.11, 12.3)] compared to GXT completers; participants who missed at Year 20 for non-medical reasons also had higher risk of all-cause mortality [HR: 2.53 (95% CI: 1.61, 3.99)]. Findings suggest that non-participation in a GXT, regardless of medical or non-medical reason, to be an important predictor of excess risk of adverse health outcomes and premature mortality. Additional patient follow-up, including identification of potential targets for intervention (e.g., weight management and smoking cessation programs), should be conducted at the point of a missed GXT.