The major purpose of any testing program is to establish repeatable differences between cultivars in a given environment but cultivars rarely perform consistently across the range of environments in which they are tested. Plant breeders recognise that the nature of genetic material and the environments in which it is tested are such that there is a lot of uncertainty involved in the selection of superior varieties. Economists have not been closely involved with the cultivar selection process and only recently has there been much interest taken by economists in the costs and management of breeding programs (Brennan et al. 1998). This paper tries to estimate long term variable costs of conducting regional variety trials and to determine the optimal number of trials for south Queensland and northern New South Wales graingrowing regions.