Eighty apparently healthy island-born Thoroughbred racehorses were evaluated using the base apex lead system of electrocardiography to characterize common T wave vectorial directions. In addition, age, sex, exercise frequency and best time record were evaluated to check if they have an influence on T wave vectorial directions. The racehorses exhibited three T wave vectorial directions – upward (53%), downward (16%) and bidirectional (31%). None of the factors like age, sex, exercise frequency and best time record contributed significantly to the changes in T wave vectorial direction. This is the first known report of common T wave vectorial directions in racehorses in the Philippines.