The Venturi scrubber is used for removing particulate matter from gaseous effluents and finds a large application in industry. The size of the droplet is of fundamental importance to the performance of the equipment. This work aims at studying the effect of some design parameters, namely liquid flow rate and liquid injection system in the droplet size and to correlate this with collection efficiency. A laser diffraction technique was used in order to measure droplet size in situ in a rectangular Venturi scrubber, with liquid injected through 1mm diameter orifices on the throat walls. Liquid flow rates of 600 and 900 ml/min and number of orifices varying from 1 to 5 were used in the experiments. The throat gas velocity was kept at 69.3 m/s. It was found that all these variables significantly affected droplet size. The results of droplet size were compared with the particle capture (collection) efficiency measured in the same experimental conditions. It was observed that the collection efficiency was affected by the liquid atomizing conditions and by the droplet distribution in the Venturi throat.