Objectives: In human heart left atrioventricular orifice is guarded by mitral valve, which lies at the junction of the left atrium and the left ventricle of the heart controlling and directing unidirectional blood flow during ventricular diastole. Irrepairable damage to the mitral valve calls for its replacement using either a valve made up of biological tissue or metal, pyrolytic carbon, vulcanised silicon rubber and similar materials. Prostheses of these synthetic valve needs detailed knowledge of mitral orifice and valve dimensions. In the present study an attempt was made to study the dimensions of mitral orifice and mitral valve in formalin fixed adult human heart specimens. Methods: Mitral orifice was cut opened in these specimens and photographed with a scale. This image was used for Scion image analysis for measurement of (i) Length of free margin and area of each leaflet, (ii). Inner circumference of the mitral valve and (iii) Surface area of the mitral valve leaflets. Results: It was found that circumference of annulus of mitral valve was 8-10 cm, length of free margin of anterior leaflet was 5-7 cm, length of free margin of posterior leaflet was 7-9 cm, area of anterior leaflet was 1-3 cm2, and area of posterior leaflet was 2-4 cm2. Conclusion: These data may be useful in designing the prosthetic valves.