BACKGROUND To compare the outcomes of mitral and/or tricuspid valve surgery in patients with previous sternotomy between those who underwent a right thoracotomy and those who underwent re-sternotomy. METHODS Between October 2009 and May 2015, eighteen patients underwent a right thoracotomy (R group) and 28 underwent re-sternotomy (re-S group). The right thoracotomy was prioritized for previous coronary artery bypass grafting. Follow-up was 100 % complete with a mean follow-up of 1.9 ± 1.5 years for the R group and 2.5 ± 1.4 years for the re-S group (p = 0.2137). RESULTS Hypothermic ventricular fibrillation was applied in 33.3 % in the R group and in 7.1 % in the re-S group (p = 0.0424). Hospital mortality, the median intensive care unit stay, and the median postoperative hospital stay were 0 % versus 7.1 % (p = 0.5130), 3 days versus 2 days (p = 0.2370), and 28 days versus 29.5 days (p = 0.8043) for the R group versus the re-S group, respectively. Although the rate of major complications was comparable (R group 33.3 % versus re-S group 25.0 %, p = 0.5401), those contents were not equal. Deep sternum infection developed only in the re-S group (3.6 %) and reoperation for bleeding was required only in the R group (11.1 %). No significant difference was observed in the 2-year cardiac-related mortality-free rate (R group 93.3 ± 6.4 % versus re-S group 90.8 ± 6.4 %, p = 0.7516). CONCLUSIONS Given study limitations, the right thoracotomy approach after previous sternotomy provided favorable outcomes as well as re-sternotomy. When selecting a right thoracotomy for re-do mitral and/or tricuspid surgery, the surgical strategy needs to be thoroughly planned.