Background: Assessment of aortic valve area (AVA) has been a critical factor in managing patients with aortic stenosis. Planimetry of the aortic valve area using transthoracic two-dimensional echocardiography has been validated; however, adequate imaging requires a skilled operator. Further, the limited resolution of two-dimensional echocardiography prevents it from delineating the aortic orifice area in most cases of aortic stenosis in adults when such conditions as calcific aortic valve are present. Purpose: To use two-dimensional echocardiography to evaluate the accuracy and reproducibility of results obtained using planimetry to assess aortic valve area and, further, to study the effects of calcification. Methods and Results: We compared results obtained with two-dimensional echocardiography with results obtained using the Doppler continuity equation method as a clinical standard. Subjects were 32 consecutive patients with possible or confirmed stenosis of the aortic valve who were scheduled to undergo two-dimensional echocardiographic examination. Thirteen of these patients had significantly calcific aortic valves, and 6 had atrial fibrillation. Measuring aortic valve area required about 1 minute with planimetry and about 4 minutes with the continuity equation method (p2). Correlation was excellent but weaker when the aortic valve was calcific (r=0.91; p2). Interobserver variability did not vary greatly in the two methods, whether the aortic valve was calcific or not. Conclusion: Although two-dimensional echocardiography showed that the accuracy of planimetry was slightly lower in cases of calcified aortic valve, the method was easy to use and proved reliable in assessing the area of the aortic valve a clinical setting.