In order to assess the antibody level of racehorses against equine influenza A2 in Sta. Ana and San Lazaro racetracks, hemagglutination inhibition tests were performed. Results showed that majority of the horses had an antibody titer less than 32 despite the mandated vaccination regimen of the Philippine Racing Commission. The study also showed that younger and older racehorses yielded titers less than 32. The recent schedule of vaccination against equine influenza virus did not elicit a higher antibody titer, leaving most of these racehorses unprotected in case of a disease outbreak.