The present study is a longitudinal study designed to explore structural relationships between anxiety, depression, personality, and background factors (e.g., gender, age, and complicated medical characteristics) in patients undergoing coronary artery bypass graft (CABG) surgery. At two timepoints before and two after CABG, 217 patients completed self-report questionnaires. To explore structural relationships, the structural equation modeling (SEM) method was applied. Using the model-generating approach, a model was developed, providing a good fit. The structural relationships revealed, in particular, the key position of neuroticism, which was related to both pre- and postoperative anxiety and depression. Relationships between anxiety and depression over time, both intra- and interrelationships, were relatively weak. Relationships between anxiety and depression at the same points in time were relatively strong, with preoperative depression leading to preoperative anxiety, and postoperative anxiety leading to postoperative depression. To provide a useful framework for development of intervention strategies, further research is needed to evaluate the plausibility of the final structural model.