Methods and Phenomena, 3: Ultrasound: Its Applications in Medicine and Biology, Part II focuses on the applications of ultrasound in biology and medicine, including irradiation, acoustic attenuation, and impedance distribution. The selection first tackles selected non-thermal mechanisms of interaction of ultrasound and biological media, therapy with continuous wave ultrasound, and pulse echo visualization. Discussions focus on imaging properties, modes of operation, rationale for selecting ultrasound as a therapeutic agent, mechanical disarrangement of tissue structures, and wave distortion. The manuscript then examines a research approach to visualization of breast tumors by ultrasound methods, acoustic characterization of tissue at the microscopic level, and intense focused ultrasound. Concerns cover systems for irradiation with intense focused ultrasound, interaction of intense focused ultrasound and biological tissue, sonomicroscopic characterization of tissues, acoustic attenuation and impedance distribution, velocity of sound distribution, and methods of procedure. The book tackles cavitation and its effects on organized mammalian tissues and thermal mechanisms in ultrasound-tissue interactions. The selection is a valuable source of data for researchers interested in the applications of ultrasound in biology and medicine.