Ventricular septal wall motion, assessed by M-mode echocardiography, was analyzed, retrospectively, in 324 patients after open heart surgery (214 patients with valvular replacement, 110 patients with aorto-coronary bypass surgery); the mean follow-up was 14 months (1 month to 5 years). In the early (less than 1 month) postoperative period, an anterior systolic (paradoxical) motion of septum (PVSM) was observed in 66% of the patients with valvular surgery, and in 76% of those with coronary surgery. PVSM disappears progressively: one year after surgery, it occurs in only 21% of patients with valvular surgery and in 16% of patients with coronary surgery. There is no significant difference in frequency and evolution of PVSM between the different types of surgical interventions (valvular versus coronary surgery; aortic versus mitral surgery; single bypass graft versus multiple bypass grafts). The similar frequency and evolution of PVSM after aorto-coronary venous graft surgery and valvular replacement surgery support the hypothesis that PVSM would be the expression of a greater anterior systolic motion of the whole heart, related to the loss of pericardial restraint. PVSM disappears slowly after surgery, probably following the development of cardiothoracic adherences.