SUMMARYAt the height of an epidemic of poliomyelities at the end of 1961, four patients were admitted to Prince Henry Hospital with the clinical syndrome of acute transverse myelitis. The level of sensory loss ascended in three patients, two of whom died. Poliovirus Type 3 was grown from the fæces of one patient, and antibody titres indicated past or present infection with poliovirus in all four patients.Histological study of the spinal cords in the two fatal cases showed the cellular changes characteristic of poliomyelitis. In addition, focal lesions were noted in the white matter of one patient.The major cause of sensory loss, which involved chiefly the modalities of pain and temperature, is considered to be the extension of cellular destruction into the posterior horns of grey matter.As there is no correlation between the annual incidence of poliomyelitis and that of “acute transverse myelitis”, it appears that it is uncommon for infection by poliovirus to present in this fashion.