The syndrome of portal hypertension represents the end point of a number of factors which causes obstruction to portal bood flow. In this paper we review the pathogenic factors associated with portal hypertension and make comments on the new invasive and non invasive techniques used to study portal hemodynamics. Special emphasis is placed on endoscopic and ultrasonographic methods (Doppler. It is now posible to obtain direct variceal pressure determinations by modifying endoscopic assessment and with new ultrasound devices we are able to obtain information by noninvasive techniques of portal patency and portal flow.