The phenomenon of turbulence suppression in a free shear layer due to controlled excitation has been studied using vortex-in-cell method. When the amplitude of the sinusoidal excitation is low, the maximum suppression occurs for excitation at the maximally unstable frequency (St// theta equals 0. 017) of the shear layer, consistent with experimental data. An interesting new result of the numerical simulation is that the above Strouhal number preference is lost at high amplitudes of excitation. Also, it is found that the level of random fluctuations superimposed on the initial sinusoidal disturbance affects the extent of suppression significantly. Refs.