Lead-cadmium, Zinc-tin and Bismuth-cadmium of (99.99%) high purity eutectic alloys were melted in a graphite crucible under vacuum atmosphere. These eutectic alloys were directionally solidified upward with a constant temperature gradient G and different growth rates V in the Bridgman type directional solidification furnace. The lamellar spacings lambda and microhardness H-V were measured from both transverse section and longitudinal section of the specimen. The variations of H-V with respect to V and lambda have been determined by using the linear regression analysis method. H-V values increase with the increasing values of V and decrease with the increasing lambda values. The Hall-petch type relationships obtained in this work have been compared with the previous works. (C) 2004 Kluwer Academic Publishers.