AbstractExperience with B scan ultrasound in the study of a series of patients admitted to the Johns Hopkins hospital for suspected occult hematomas has been reviewed. Patients included in this report acquired hematomas primarily as the result of medical or surgical therapy. The ultrasonic appearance in most patients is that of a cyst, due to unclotted or homogeneously clotted blood which generates no internal echoes. As soon as fragmentation of the clot occurs, internal echoes are usually found. B scanning was of value in detection, localization and follow‐up of hematomas and was the only diagnostic test used in seven of eleven cases.The advantage of this technique for diagnosis and follow‐up are related to the simplicity of the procedure, its lack of sideeffects and low c