This volume contains papers selected from contributions made to the Fourth Symposium on "Applications of Laser Anemometry". It is divided into three chapters concerned respectively with single-phase flows, two-phase flows and instrumentation. In the first chapter, the papers are concerned with fundamental investigations of shear flows as well as important applications including the Earth's boundary layer and internal combustion engines. The two-phase flows include applications of amplitude- and phase-based techniques to the sprays of Diesel and gas-turbine engines and to a fluidised bed and slurry flows. The new instrumentation includes miniature and multipoint LDV arrangements, PIDV and photochromic visualisation as well as improved explanations of laser-based systems.