A GLP study, which formed the Australian component of a Global Residue Project (GRP), was commissioned through collaboration between HAL and the USDAs IR-4 project. The main objective of the GRP was to determine the impact of regional influences on pesticide residue analysis in produce collected from field-studies. Thus, the same study plan (protocol) was followed by all 20 collaborating countries. The Australian component of the GRP was conducted as a single GLP study that included two field-sites. The project determined the impact of regional influences on the residues of 4 pesticides that remain in tomatoes when the same pesticide application and crop sampling protocol is used in each of the 21 locations.