Although the surface roughening transition in single component systems has been studied extensively, the surface roughening transition in binary alloys has not. We have conducted a kinetic Monte Carlo computer study to simulate alloy crystallization using the spin-one Ising Model with diffusion. The surface roughness, which is defined as the density of lateral unsatisfied bonds at the interface, has been determined for both the pure components and for alloys of various compositions. The surface roughness for a pure material depends on the change in bond energy associated with the transformation, divided by the melting point. The solid phase contains essentially one component, the surface roughness of the alloys was found to depend on the change in bond energy of the pure component, divided by the liquidus temperature of the alloy. (C) 2002 Elsevier Science B.V. All rights reserved.