Mycotoxins are toxic chemicals produced naturally by a wide range of fungi. The best known of these, the aflatoxins, are potent liver carcinogens in both human and animal subjects. It is well known overseas that mycotoxins occur in maize and their occurrence is related to exposure of the developing kernels to high temperatures and drought stress. Australian-grown maize is used in both human food products and animal feed. An analytical survey was conducted to ascertain the extent of mycotoxin contamination of maize growing in the major Australian maize growing regions. The survey which included North Queensland, the South Burnett, the Darling Downs, northern and central NSW and the Murrumbidgee Irrigation areas over the 2004, 2005 and 2006 growing seasons, is the largest and most comprehensive survey to date. Samples were analysed for a range of mycotoxins, including aflatoxin B1. Concentrations of aflatoxin contamination were correlated with climate data provided by the Australian Bureau of Meteorology and a significant relationship with periods of low precipitation was identified. The implications of this correlation in the context of climate change in Australia are discussed.