In this paper we soncider the effect of using bus interconnetion structures on the overheads presnent in conservative parallel simulations of multicomputer programs. We use a modified version of the poker programming environment to empirically measure the overhead in three parallel algorithms using buses . We discuss the source of overhead and compares the with those found using point - to-point communication. Preliminary results indicate that the overheads encountered using a bus interconnetion structures were not predicted by our previous results using point-to point communications