An observation was made over a period of two years, that the patients who underwent aortic valve replacement with bioprosthetic valve had post-operative moderate trans valvular gradients with NYHA CLASS II. Observation: There were total of 30 patients who underwent bioprosthetic aortic valve replacement over a period of 2 years. All patients were above 50 years. Mostly St.judes and Perimount bioprosthetic valves were used. In the post-operative period it was observed that 5 patients in their first post-operative day, developed hemodynamic unstabiliity. Post-operative echo was done it revealed moderate to severe stenosis. Patients were managed conservatively and discharged and kept on follow up. On follow up ECHO it was seen that there was moderate stenosis in all 5 patient and out of other 25 patient, it was observed that 6 patients had moderate stenosis with NYHA class II. Conclusion: Bioprosthetic aortic valve replacement was standard treatment, but in patients it was observed that they remained in moderate stenosis and NYHA class II in early post-operative period and follow up. Reason remained unidentified. Limitation As it is an institutional study and small number of patients were included. More over duration of study was short over period of 2 years.