In-hospital rehabilitation can improve recovery of patients after surgery, but also contributes to the high costs of the German health system. A telemedicine-based rehabilitation used in the home as an alternative to in-hospital rehabilitation was evaluated in a pilot study. In an open trial, 170 patients performed a 3-month ambulatory rehabilitation after cardiac surgery. There were two groups (group 1 [n = 70] and group 2 [n = 100]). Group 1 participated in conventional in-hospital rehabilitation. Group 2 received ambulant rehabilitation using telemedicine. Physical performance, quality of life, (measured with a questionnaire), complications and costs were assessed and compared between the two groups. Maximal physical performance (MPP) was assessed at 6 and at 12 months after cardiac surgery. It was significantly increased by 46-54 watts in both study groups compared to their baseline value. Moreover, physical and psychological quality of life had increased in both study groups compared to baseline values. However, group 2 was the only group to show statistical significance in all categories. Fewer incidents of angina pectoris were reported within the study interval in group 2 compared to group 1 (p < 0.01). The total cost of rehabilitation was 58% lower in group 2 compared to group 1. Ambulatory rehabilitation using telemedicine improves physical performance, quality of life, is safe, and is inexpensive. Our data indicate that home-based rehabilitation is more effective than in-hospital rehabilitation for patients after cardiac surgery.