Exercise-based cardiac rehabilitation (ECR) is characterised by low attendance and completion rates. We investigated factors associated with patient not attending or completing ECR in a university hospital. In an observational study, data were obtained from clinical and administrative databases and medical records. Participants with ischemic heart diseases, heart failures, or heart valve diseases were referred to ECR between 2008 and 2011. Patients were considered as non-completers if not attending or attending < 13 of 16 sessions. Analyses included logistic regression adjusting for age and gender. Out of the 404 referred, 47% did not complete ECR. Smokers: adjusted odds ratio (AOR): 2.14 (95% confidence interval (CI), 1.18 – 3.89), obese: AOR: 1.94, (95% CI, 1.09 – 3.48), prescribed antidepressants: AOR: 1.87 (95% CI, 1.03 – 3.39), living alone: AOR: 1.66 (95% CI, 1.07 – 2.55), and non-surgical treatment: AOR 1.66 (95% CI, 1.09 – 2.59) were associated with not completing ECR. Social vulnerability should be taken into consideration in future ECR’s.