OBJECTIVES: Cardiac surgery has little effect on life expectancy in elderly patients. Thus, improving the quality of life should be the main factor affecting therapeutic decisions. Most studies on quality of life in elderly patients undergoing cardiac surgery report improvement but have limitations. Consequently, we assessed improvements in the quality of life of elderly patients undergoing elective cardiac surgery, identified influencing variables and established patterns of mental and physical health variations in the first year postoperatively. METHODS: We conducted a prospective study of patients aged 65 or older who underwent elective cardiac surgery between September 2011 and August 2013. The 36-item Short Form (SF-36) surveys were obtained preoperatively and at 3, 6 and 12 months postoperatively. RESULTS: The 430 preoperative patients with a mean age of 74 years (SD 5.5 years) comprised 220 men. Most physical health improvements occurred within 3 months and continued to improve significantly until 12 months. Predictive variables for patients showing less improvement were poor preoperative physical health, female sex, older age and longer length of hospital stay. Mental health improved significantly through the third postoperative month. The negative predictive variables were poor preoperative mental health and longer intensive care unit stay. CONCLUSIONS: Most patients improved both physically and mentally after surgery, and most of the improvement occurred within 3 months post-surgery. These improvement patterns should be taken into account when creating rehabilitation programmes, and patients should be counselled on what improvements can be expected during the first 12 months after surgery.