We compared the preoperative status, operative factors, and postoperative outcomes among patients having mitral valve operations with three atrial incisions. The incisions were right lateral (n = 66), superior septal (n = 46), and transseptal (n = 37). Differences in patient and operative factors among the groups were not predictors of adverse postoperative outcomes with multiple regression analysis. Postoperative pulmonary failure was less common in the superior septal group. Patients in the superior septal group more commonly required permanent pacemakers than those in the right lateral group. In patients with sinus rhythm before operation, sinus rhythm had returned before hospital discharge more commonly in those in the right lateral group (35 of 44, 80%) than in those in the superior septal group (18 of 28, 46%) or in the transseptal group (9 of 13, 69%). With multiple regression analysis the type of atrial incision was not a predictor of postoperative pulmonary failure or need for permanent pacemaker. Right lateral and transseptal atrial incisions were predictors of retention of sinus rhythm after operation. We conclude that the results of superior septal incision are comparable with those of other incisions except for a slightly greater risk of loss of sinus rhythm. One must weigh the technical advantages of the superior septal incision against the risk of loss of sinus rhythm.