This paper deals with the residence time distribution (RTD) in a non-intermeshing counter rotating twin screw extruder. The RTDs were measured in three vent zones of the extruder separately, and in the adjacent zones combined, using a soluble dye as the tracer. Assuming that the RTDs in the adjacent zones are independent of each other, the overall RTD was also calculated using a previously developed statistical theory. The theory has also confirmed the consistency of the present measurements. A predictive RTD model for the non-intermeshing twin screw extruder, based on the flow analysis of the individual screw zones and their statistical superpostion, was also developed. The predictions are in good agreement with experiment.