1. Three neutral oligosaccharides were obtained from horse colostrum by ion-exchange, activated charcoal column and preparative paper chromatographies. 2. The following structures were elucidated by methanolysis, methylation analysis and 75 MHz 13C-NMR spectroscopy; Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc (HM-3a), Gal beta 1-4GlcNAc beta 1-6Gal beta 1-4Glc (HM-3b) and Gal beta 1-4GlcNAc beta 1-3[Gal beta 1-4GlcNAc beta 1-6]Gal beta 1-4Glc (HM-5). 3. HM-3a and HM-5 have been found in human milk, named as lacto-N-neotetraose and lacto-N-neohexaose, respectively. HM-3b has been isolated from goat milk. 4. An homology and heterogeneity were assumed among the following animal species' milk oligosaccharides: horse, human, goat and tammar wallaby.