The increase of B4C addition into an AA6061-B4C composite system will not be always an ideal choice for improved properties because of the issues related to incorporation, distribution and interfacial wetting while stir-casting. In such a case, ultrasonication is considered to be an alternative to get the advantage of microstructural changes which in turn improve the properties. In the present study individual B4C distribution and the refinement of microstructure was achieved at 4wt.%B4C. The improved specific ultimate and compressive strengths at 4wt.%B4C were observed as 36.32% and 43.92% whereas specific Vicker's and Brinell hardness as 53.41% and 50.89% respectively.2009 Elsevier Ltd. All rights reserved.