A time course study was made of the development of Fusarium infection and the appearance of the three Fusarium toxins, nivalenol (NV), deoxynivalenol (DON) and zearalenone (ZEN), in various fractions of maize plants from two sites in New Zealand, one in the Manawatu region and one in the Waikato. Fusarium infection was seen in leaf axil fractions in January, at the time of tassel emergence, and was detectable in stalks, leaf blades, rachis and peduncles during February and in kernels in April. NV, DON and ZEN were only detectable some time after infection was demonstrable. NV, in high concentrations relative to DON (up to 287 mg/kg for NV and up to 8 mg/kg for DON), was found in fractions from the Manawatu site where F. crookwellense and F. culmorum were the predominant toxigenic species. NV and DON at similar levels (up to 25 mg/kg) were found in fractions from the Waikato site at which F. graminearum and F. subglutinans predominated. Highest levels of NV and DON were in rachis and peduncle. ZEN was found most consistently in leaf axils and blades at both sites (up to 8 mg/kg at the Manawatu site and up to 75 mg/kg at the Waikato site) but at times there were high levels in rachis fractions (up to 417 mg/kg at the Manawatu site).