The aim of this study was to assess the diagnostic accuracy of transthoracic (TTE) and transesophageal echocardiography (TEE) for the detection of atrial masses. The authors' own experiences with the use of TTE and TEE images in the assessment of atrial masses are reported. These masses included tumors, thrombi, and valvular vegetations. The study groups consisted of 14 consecutive patients (7 women an 7 men), age range 24-72 (mean age 56.6 < +13.4) years. Eleven patients had left atrial tumor, two patients had atrial thrombi, and one patient had vegetation in left atrium detected with TEE. Eight patients had left atrial myoma, two patients had right atrial myxoma, and one patient had right atrial leiomyosarcoma. There was no false negative and no false positive TEE diagnosis, yielding a 100% sensitivity and specificity of TEE in detecting atrial masses. TEE detected atrial masses in six (43%) patients, provided poor images in five (36%) patients, and failed to reveal atrial masses in three (21%) patients. The TEE diagnosis was confirmed by surgery and pathohistology in all patients. The ability of TEE to visualize both atria with great diagnostic accuracy makes it a very valuable procedure in the assessment of atrial masses.