In livestock populations, estimation of breeding values for selection requires a matrix describing the additive relationship between individuals in the population. This matrix can be derived from pedigree information. In some livestock populations, pedigree information may be unavailable, incomplete, or in error. Here we use simulated data to demonstrate that marker-derived relationship matrices can be used to predict breeding values and estimate additive variance components, provided the markers are sufficiently dense. The approach is demonstrated for an Angus data set with 9,323 SNP markers genotyped.