The introduction of two-dimensional echocardiography (echo 2D) complemented by doppler techniques has allowed to assess the dynamic function of the heart. However in 10-15% patients the standard transthoracic method (TEE) does not provide complete echocardiographic image due to obesity, emphysema and deformations of thorax. These difficulties have been later overcome by transesophageal probe, but it made the examination possible only in one plane-monoplane TEE (m-TEE). Transesophageal echocardiography the biplane probe (bi-TEE), introduced in late 80s has permitted the heart and aorta visualization in two perpendicular planes: transverse (T) and longitudinal (L). The purpose of our study was to establish the diagnostic value of biplane transesophageal echocardiography in comparison with hitherto existing monoplane echocardiography (transverse plane). The study group consists of 60 patients (aged 19-78 years) with various diseases of heart and aorta. We performed biplane transesophageal examinations with the use of Aloka SSD-870 echocardiograph connected with the biplane probe (45 patients) or new, prototypical matrix probe (15 patients). For the heart and aorta assessment the typical projections were used. The advantages of biplane TEE compared with monoplane TEE are as follows: 1) more favorable left ventricular examination, 2) better assessment of the heart apex, 3) the ability to investigate the right heart; tricuspid valve, right ventricular outflow tract, pulmonary valve, pulmonary trunk and right pulmonary artery, 4) precise imaging of both atrial' structures: cavities, intraatrial septum, foramen ovale, left atrial appendage, venae cavae and pulmonary veins, 5) possibility of thoracic aorta diagnostics, especially in ascending aorta.(ABSTRACT TRUNCATED AT 250 WORDS)