This review covers the egg production models used in poultry. Similarities and discrepancies among the models are illustrated using a real data obtained from a layer breeder flock. Egg laying in poultry begins at sexual maturity and quickly reaches peak production, and then declines with hen age. For many years, egg production studies have been carried out for the purpose of modelling. Some of the functions were developed for this purpose, such as nonlinear regression equations (Gamma, McNally, McMillan, Adams-Bell, Compartmental, Modified Compartmental, logistic-curvilinear, Gloor, Lokhorst, Narushin-Takma) and some Multiphasic (Segmented Polynomial, Persistency, Individual). Almost all of these functions have been developed to allow modelling on the basis of flock averages. Most models having empirical structure and a small number of parameters are considered biologically meaningful. New models are currently required to be useful for both individual egg yields and to contain biologically relevant parameters.