Equine herpes myeloencephalopathy has been confirmed in the Regional Municipality of Niagara, Ontario. A 7 year old Thoroughbred mare developed ataxia that progressed and she was subsequently euthanized. The following day, in a separate barn, another mare became acutely neurologic and recumbent. She was also euthanized. No other horses have displayed neurologic signs however there have been a few horses with a fever. PCR testing on both neurologic mares confirmed equine herpesvirus 1 infection. The facility owner has instituted voluntary animal movement restrictions and biosecurity procedures.