This paper deals with the effects of kinematic viscosities of lower and upper fluid, square of the Alfv n velocity, the medium porosity and the medium permeability on the instability of superposed viscous fluids in hydromagnetics saturating porous medium. Graphs are plotted by giving permissible numerical value to the non-dimensional parameters. The imaginary growth rate of the perturbations increases with the increase in kinematic viscosities of the lower and upper fluid implying thereby destabilizing effects on the system. The imaginary growth rate of the perturbations decreases with the increase in the square of Alfv n velocity and medium permeability parameter, respectively. The magnetic field dissipates the energy of any disturbance more than that carried out by medium permeability. In other words, the role of medium permeability parameter shows stability on the Kelvin-Helmholtz instability problem, while the magnetic field plays the fundamental role to generate the complete stability.