Ultrasound is a widely used imaging modality in medical practice for the diagnosis and staging of diseases. In the last decade it has benefited from major advantages in technology, and three dimensional ultrasound has been developed. This new modality is rapidly achieving widespread application in numerous situations since it helps to overcome some limitations related with two dimensional imaging. The developments in high speed computer technology have improved volume data acquisition, imaging and storage. It is believed that volume ultrasound will be a routine part of the diagnosis and treatment of patients with the proven advantages owing to its basic working principles. In this paper we attempt to describe the working principles of three dimensional ultrasound, developments in a number of three dimensional imaging systems, reconstruction and viewing methods, documentation, volume measurement methods, and discuss various clinical applications with some examples.