"Neonatal foal septicemia" is a term used in current literature to embrace a wide variety of diseases, their infective routes, causative agents and associated presentations. Diagnoses of primary Actinobacillus equuli, Escherichia coli, Streptococcus zooepidemicus, Salmonella aboertivo equina, Staphylococcus aureus, Serratia marcescens, Pasteurella sp. and Clostridium sp. have at times been cited as the agent in this intricate disease complex with conflicting data. Commonly the foal with bacterial sepsis presented during the first two weeks of life, i.e. the neonate, can be given a poor prognosis for survival. Both morbidity and mortality rates are high. A survey of equine neonates presented to the Large Animal Clinic at the New York State College of Veterinary Medicine from 1 January 1975 to 15 October 1985 revealed a case-fatality rate of 76.4%, very close tot he 74% reported by other authors. The purpose of this paper is to familiarize the reader with the typical clinical presentation, pathophysiology, laboratory values and post-mortem lesions of neonatal foal septicemia. Specific etiologies, differential diagnoses and treatment will also be addressed.