Objective The mitral valve may be accessed directly through the left atrium but visualisation can sometimes be challenging. A trans-septal interatrial approach provides better exposure and easy access for concomitant tricuspid procedures especially in difficult cases. This retrospective study evaluates the safety and effectiveness of the extended vertical trans-septal approach (EVTSA) for routine mitral valve exposure. Method 1017 consecutive patients undergoing an isolated primary mitral valve procedure (repair/replacement) through a median sternotomy were retrospectively studied between 2000 and 2015. Up to 135 patients were operated by EVTSA (group A) while 882 patients underwent a traditional left atrial (LA, group B) approach. Results There were 135 patients (M/F=56/79) in group A and 882 patients (M/F=398/484) in group B. Logistic EuroSCORE was significantly lower in EVTSA group (0.61 vs 0.90, p=0.000001). In the LA group there were more patients with preoperative transient ischaemic attack or stroke (94 vs 6, p=0.005). Cumulative cross-clamp time was 82 (44-212) min (EVTSA group) and 78 (30-360) min (LA group) (p=0.271) while cardiopulmonary bypass time was 107 (58-290) and 114 (43-602) min, respectively (p=0.121). Postoperative blood loss was 415 mL (EVTSA) vs 427 mL (LA) (p=0.273). No significant difference was found in the incidence of postoperative atrial fibrillation (p=0.22) or heart block requiring permanent pacemaker (p=0.14). Conclusion In our opinion, EVTSA to the mitral valve is safe and reproducible. It gives excellent exposure of the mitral valve under all circumstances without any significant increase in cross-clamp or bypass time, postoperative arrhythmia, heart block/pacemaker rate or bleeding.