Background: Heart valve operations during pregnancy still have some significant risks for mother and child. Cardiac operations during the third trimester of pregnancy more confident than the first and second trimesters. If a valve treatment needed during the first and second trimesters trans-catheter valve interventions can be preferred. Valve operations can be performed with the use of cardiopulmonary bypass which has a foreign surface that contacts with blood and causes a systemic inflammation. On the other hand patients had a linear flow which provides an arterial tension between 50 to 80 mm Hg during the cardiopulmonary bypass. Methods: Between 2000 and 2012 6 patients who had mitral valve operation during their pregnancy were evaluated. Out of 2 cases had a mitral valve replacement with a mechanical valve before the pregnancy. They had severe pulmonary edema and stuck valve needing urgent delivery of the child and on-pump cardiac operation. Remaining 4 patients had severe pulmonary edema because of mitral stenosis (3 cases) or mitral regurgitation (1 case). Out of 1 patient had successful transcatheter mitral balloon valvuloplasty, while an other patient had unsuccessful balloon valvuloplasty and needed urgent closed commissurotomy with left thoracotomy. Results: There were no deaths among the patients. Out of 2 cases had sectio and healthy childs after interventions. Among these cases one of them had a mitral balloon valvuloplasty. The other patient had a 24 week pregnancy, severely calcified mitral stenosis and pulmonary edema needing urgent mitral valve replacement with a mecahnical valve. The operation was performed by using the cardioplumonary bypass with a pulsatile pump flow and continous intrauterin monitoring of the child during and after the operation. The patient and child did well after the operation, 12 weeks later she had a successful sectio and a healthy girl. Out of 4 patients had urgent heart valve operations which can not protected the life of child, even one patient had a closed mitral commissurotomy without using the cardiopulmonary bypass. Conclusion: The timing of open heart surgery is very significant in pregnancy. Open heart surgery after the delivery of the baby with sectio is the most advised method, if possible. However, urgent surgery may be needed before maturation of fetus, in this situation cardiopulmonary bypass may be used with pulsatile flow in order to protect the life of child during and after the early term of open heart surgery.