Problems with egg quality have resulted in large economic losses to the egg industry. Studies have been conducted to provide realistic commercial guidelines on the internal and shell quality of the eggs, for the Australian Egg Industry. Eggs were obtained from commercial operations, both from flocks that were followed throughout their laying life (longitudinal studies'), and also from flocks that were sampled at that were age one and across a range of ages of flocks (cross-sectional studies'). A total of almost 25,000 eggs were used. Eggs were analysed individually for internal quality and egg shell quality as soon as possible after collection using specialized equipment from Technical Services and Supply, U.K. The data collected indicate that there is considerable variation among flocks in egg and egg shell quality measurements, although there is little difference among the three main brown egg layer strains currently used in Australia (Isa Brown, HyLirie Brown, HiSex Brown). However, consistent findings in relation to bird age were: an increase in egg weight and shell weight up to 45 and 40 weeks of age, respectively, after which these weights remained relatively constant. Shell colour, shell breaking strength, deformation, percentage shell, albumen height and Haugh Units all declined with hen age. Eggs lost weight during storage and this was influenced by storage time, temperature and humidity. Haugh Units also deteriorated during storage and this effect was accentuated at higher storage temperature but was not greatly influenced by humidity.