Building upon scientific discoveries of past years, B-scan ultrasonography has become a widely accepted diagnostic procedure that has assumed particular importance in the areas of obstetrics and gynecology, internal medicine, and urology. The early and liberal use of the method, even for outpatients and in outlying hospitals, is in accordance with the safety and the relatively low costs of diagnostic ultrasonography. Perhaps more than in any other method, however, the user of diagnostic ultrasound must possess a great deal of technical expertise if the equipment is to be operated properly and the ultrasonic images interpreted correctly. It is little wonder, therefore, that training has not entirely kept pace with the burgeoning sophistication and popularity ofthe technique. With this in mind, it is our intention to supplement available text- books and atlases with a guide that offers a basic, practical survey of ultra- sound techniques in the areas of internal medicine, obstetrics, and gyne- cology. Basic physical and technical principles are discussed only to the extent necessary for understanding the technical control features of ultra- sound equipment. A brief glossary is also provided for this purpose. In the section on Special Diagnosis, we have intentionally adhered to a rigid for- mat consisting of Examination Technique, Normal Findings, Pathologic Findings, Differential Diagnosis, Diagnostic Applications, and Potential Difficulties, recognizing that some repetition would be necessary in various organ-specific chapters. This will enable the user to locate quickly the information that is pertinent to a specific examination procedure.