The Venturi scrubbers have a high collection efficiency to remove very small particles from gaseous streams. The main purpose of this work is to determine the overall collection efficiency of Venturi scrubbers with circular section under different operation conditions. The experimental system consisted of a Venturi scrubber with circular section and liquid injection in the throat. A factorial experimental design was carried out; the overall collection efficiency was the response. Three variables were analyzed: the throat length, the air velocity and the liquid flow. The best values for efficiency were obtained for 15 m/s of air velocity and 300 mL/min of liquid flow and the throat length did not have influence.