Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors belonging to the nuclear hormone receptor superfamily. Recent studies have demonstrated that PPARs regulate lipid metabolism and are expressed in various cancers. The aim of the present study was to investigate the expression of PPAR-alpha, -beta and -gamma in normal canine testicular tissue and canine testicular tumours (CTTs). Expression of PPAR-alpha, -beta and -gamma was greater (P <0.05) than in normal testicular tissue. PPARs were therefore induced in CTTs and they may play a role in the biology of these tumours. (C) 2012 Elsevier Ltd. All rights reserved.