Based on the experience with over 600 abdominal B-scan echograms, diagnostic principles and signs are discussed. These include: requirements for complete mapping of the abdomen; and demonstration of the lesion in scans obtained in 2 planes and at several instrument sensitivity settings. Certain characteristic echographic appearances can be correlated with the underlying pathophysiologic or anatomic changes and are discussed as "echographic signs." These include: the through-transmission sign; the mass outline sign; the double contour sign; the absent contour sign; the compressed tissue sign; the intraorgan echo sign; and the distribution pattern sign. The use of echographic scanning as a diagnostic method rather than as a novel display of known pathology cannot be overemphasized. Systematic approach to patient examination and scan interpretation is needed for consistent and correct diagnoses.