Crop Field Trials (also referred to as supervised field trials) are conducted to determine the magnitude of the pesticide residue in or on raw agricultural commodities, including feed items, and should be designed to reflect pesticide use patterns that lead to the highest possible residues. While the OECD Guideline for the Testing of Chemicals on Crop Field Trial (TG 509 published in September 2009) provides a harmonised approach to conducting and reporting crop field trials in OECD countries, this Guidance Document on Crop Field Trials will help in planning the trials in OECD countries and in interpreting the results.