Abstract: In a chaff missile engagement scenario the number of chaff elements or dipoles in the missile seeker radar resolution cell (RRC) changes dynamically. To capture this effect in simulation a technique is proposed in this paper to estimate the number of effective chaff dipoles. Estimation using this technique caters for the dynamically changing positions and dimensions of both the chaff cloud and the missile seeker RRC. This proposed technique is based upon the Monte-Carlo simulation method, and its validation has been completed by comparing the analytically computed and the estimated values for different geometric positions of the systems. A chaff missile engagement scenario has been simulated to show the application potential of this technique in estimating the chaff cloud radar cross section (RCS).