It is demonstrated in this work that gas-phase velocity measurements can be performed in dense sprays by using a new 2D laser-based flow tagging technique. Velocity measurements in dense sprays, such as automotive direct injection (DI) Otto and Diesel sprays, are difficult with conventional techniques because of the high number densities of droplets, the optical thickness of the medium, and multiple light scattering effects. The present flow tagging technique is performed by two consecutive laser pulses, i.e., `write' and `read' lasers. The write laser creates a grid of tracer molecules (NO) by inducing a photodissociation process. The tracer molecules are convected with the flow and probed by the read laser after a certain delay. The instantaneous velocity field is determined by time-of-flight analysis.