Cathelicidins are a family of gene-encoded antimicrobial peptides found in mammals. Seven cathelicidin genes have been identified in sheep, but up to now only two variants of one of these predicted peptides (OaBac5) have been purified from ovine neutrophils. In this work numerous proline/arginine-rich cathelicidin peptides were purified, including the originally predicted OaBac5 and another OaBac5 variant. As well as this, the C-terminus of the predicted OaBac7.5 and various truncated forms of OaBac11 were purified. Even though these peptides were much smaller than those predicted, they still displayed antimicrobial activity. (C) 2003 Elsevier Inc. All rights reserved.