A review of the diseases caused by Malassezia pachydermatis has led to the conclusion that the yeast is an opportunistic pathogen that depends on predisposing host factors and different immune suppressive mechanisms for clinical manifestation. Until recently, the role of M. pachydermatis in seborrhoeic dermatitis and otitis externa in dogs has been largely unrecognized. The clinical manifestation, aetiology, diagnosis and treat ment of disease conditions in dogs caused by M. pachydermatis are reviewed. Human Malassezia furfur infections are briefly described.