Trends of development of technical diagnosis methods are discussed, and experience of use and development of new technologies of acoustic monitoring of pipelines based on the use of waveguide properties of the monitored object is described.Technical diagnosis methods based on the use of physical phenomena and fields or physical monitoring methods are an important element in assuring industrial safety of technical devices and, in particular, pipelines.Current development of science and technology makes it possible to create, based on these methods, information technology -a combination of methods of getting, processing, transforming, transferring, and presenting information (Fig. 1). In practice, this term is used in a narrower sense for solving the referred tasks.In fact, practically all physical monitoring methods are used with the aid of computer engineering, which helps enhance their efficiency and reliability to a great extent, and computing capacity of computer helps acquire information or present it in visual (graphic) form.In developing diagnostic technologies, two basic directions can be distinguished: first -solving problems of enhancing reliability and sensitivity of monitoring; second -solving problems of enhancing efficiency and technological viability of the methods.Technologies of the first direction are, in greater part, in the domain of classical concepts of nondestructive monitoring (NM): based on magnitudes of detected defects, sensitivity, volumes, and efficiency of monitoring. Classical ultrasound still occupies the dominant place in NM (about 30% of the total volume of monitored objects). Ultrasonic method is implemented to a large extent by computerized devices, which allows one to consider it as information technology having a large database with respect to adjustments of sensitivity and makes it possible to store, process, and record monitoring data. To be distinguished, in particular, are devices and methods that use of B-and C-scanning and, consequently, implement special schemes of sounding and have transducer positioning system.Technologies targeted to spatial visualization of detected defects with the aid of mosaic (multielement) transducers can be combined under a common term -aperture synthesis method.The technologies of the second direction relate to development of express diagnostics, which disclose highly dangerous defects of considerable sizes. The efficiency of these methods is one order of magnitude higher than the classical, but in terms of number of detected defects, they are generally inferior to the classical.