Abstract. The droplet size distribution (DSD) in a swirl flow field formed by guiding vanes in a vane-type pipe separator (VTPS) was experimentally studied. The cumulative volume fraction and maximum droplet diameter of the dispersed phase were determined using a laser particle size analyzer. The results show how the characteristics of droplets in a swirl flow field changes with the dispersed phase content, flow rate and water velocity at the inlet. A quasi-power law function is shown to fit the DSD cumulative volume fraction results better than the Rosin-Rammler Function.