After the first two successful editions of the Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering (ISUD), held at PSI, Villigen, Switzerland in 1996 and 1999, we are very pleased to organize this third edition for the first time at the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland. In a certain sense, present Ultrasonic Doppler technique users will come to the place where some of the bases of this technique were elaborated. The ultrasonic Doppler method for velocity profile measurements has recently shown its potential in the fields of general fluid mechanics and fluid engineering. Its application has been broadened from fundamental research to industrial use. It is attracting increasing interest from physicists and fluid engineers for its use as a research tool and the number of users is growing. The purpose of the Symposium is to exchange information on applications of the ultrasonic Doppler method to a variety of flow configurations and liquids including industrial measurements. The Symposium brings together researchers from all over the world to discuss their applications, results and future work using the ultrasonic Doppler method. The submitted papers present the latest fluid mechanics results that are based on the ultrasonic Doppler technique. In recent years non-Doppler ultrasonic measurement methods have emerged for quantifying various physical parameters. A special section is dedicated to these applications.