BACKGROUND: Patients who undergo cardiac valve surgery undertake routine physical therapy program. Despite its routine use, its influence on physical activity level post- surgery has not been illustrated. This study was to investigate whether 5 days of in-hospital physiotherapy could improve physical activity levels after cardiac valve surgery. METHODS: The study is a single-blind randomized controlled trial which performed in Cardiothoracic Surgery Department. Patients who underwent cardiac valve surgery (n=34) for confirmed cardiac valve disorders were assessed during hospitalization. The intervention group received a daily post-operative physiotherapy intervention, consisting of individualized mobilization, breathing exercises, ambulation with or without a walking aid. There was no physiotherapy treatment in the control group. Measurements: physical activity was assessed with the handgrip strength test and the timed up and go test. RESULTS: The treatment group showed significantly greater handgrip strength [20.58 (7.17) vs. 12.96 (4.65) kg] and less time on the timed up and go test [5.92 (2.91) vs. 6.53 (1.60) s] compared to the control group on the 5th post-operative day. Whilst there was no significant difference on the timed up and go test between the 2 groups, handgrip strength on the 5th post-operative day was significantly different between the 2 groups. CONCLUSIONS: Patients who received physiotherapy during hospitalization showed increased levels of handgrip strength and physical activity on the 5th day after cardiac valve surgery compared to the control group. The clinical value of increased levels of physical activity after in-hospital physiotherapy following cardiac valve surgery requires further investigation.