Electroretinography is a technique used for the objective assessment of retinal function and is useful as an auxiliary diagnostic tool for various ophthalmopathies. We report here information about the indications, components and measurements of the electroretinogram (ERG) and about the flash ERG technique illustrated by the Classic/Standard protocol used in the Ophthalmology Unit of the “Governador Laudo Natel” Veterinary Hospital, Faculdade de Ciências Agrárias e Veterinárias, State University of São Paulo (UNESP), Jaboticabal Campus.