Principle purpose of this lecture is to presentation on Ultrasonography. Here discuss on the velocity of propagation of ultrasound through a medium depends upon its compressibility. Also analysis wave of ultrasound may get reflected, refracted, scattered, or absorbed as it propagates through a body. Most modes of diagnostic ultrasonography are based upon the reflection of ultrasound at tissue interfaces and a gel is used to minimize the presence of air between the transducer and the skin to avoid reflection at the skin surface. Finally briefly explain modes of Operation, Umbilical cord and Echocardiography.