Background: Cardiac magnetic resonance tomography (CMR) is a new imaging technique capable of imaging the aortic valve with high resolution. We assessed the aortic valve area (AVA) in patients with aortic stenosis (AS) using CMR and compared the results to those obtained by transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE). Methods: Forty-two patients (36% female, 71 ± 8 years) symptomatic for AS underwent TTE followed by TEE to determine the AVA; the continuity equation was used with TTE and the planimetry technique with TEE. In 26 of these patients, the AVA was additionally obtained by CMR planimetry. Results: The mean AVA derived by TTE, TEE and CMR were 0.74 ± 0.27, 0.87 ± 25 and 0.97 ± 0.30 cm<sup>2</sup>, respectively. The mean absolute differences in AVA were 0.13 ± 0.19 cm<sup>2</sup> for TTE vs. TEE, 0.21 ± 0.25 cm<sup>2</sup> for TTE vs. CMR and 0.05 ± 0.11 cm<sup>2</sup> for CMR vs. TEE. Conclusion: There is a good agreement between CMR and the echocardiographic determination of the AVA. If multicenter, large-scale studies confirm these observations, CMR could serve as a noninvasive alternative to TTE/TEE for the assessment of AVA in AS.