Porcine hemagglutinating encephalomyelitis virus (PHEV) is a neurotropic Betacoronavirus that primarily infects pigs, leading to severe neurological and gastrointestinal diseases, particularly in piglets of less than 2 weeks old. First identified in Ontario, Canada, in 1957, PHEV is responsible for vomiting and wasting disease (VWD) and encephalomyelitis. The virus is a positive-sense single-stranded RNA virus, encoding five structural proteins: hemagglutinin-esterase (HE), spike (S), membrane (M), nucleocapsid (N), and small membrane (E). PHEV spreads through aerosols and vertical transmission from sows to neonates, primarily targeting respiratory epithelial cells and neurons. Clinical signs include reluctance to suckle, vomiting, anorexia, hind limb paralysis, and severe neurological symptoms, often leading to high mortality rates. Pathological findings in infected pigs include neuronal degeneration, perivascular cuffing, and gliosis. Diagnostic methods encompass molecular tests, virus isolation, and serological tests. Despite widespread global prevalence, PHEV outbreaks are relatively rare, with subclinical infections persisting in many regions, notably America and Asia. No vaccines are currently available, and control measures rely on surveillance and biosecurity. Although no human infections have been reported, genetic analyses suggest potential interspecies recombination events. Understanding PHEV’s pathogenesis and immune evasion mechanisms is crucial for developing effective prevention and control strategies, thereby mitigating its economic impact on the swine industry. This chapter provides a comprehensive review of PHEV, covering its history, etiology, epidemiology, clinical signs, pathology, pathogenesis, diagnosis, immunity, prevention, and zoonotic potential.