The majority of the farmers in this sample of Thai farmers did not use sufficient self-protective behaviors when using the organophosphate insecticide chlorpyrifos. Most were directly exposed to chlorpyrifos, potentially leading to illnesses. The aim of this study was to improve safety behaviors when using chlorpyrifos by an occupational health education program. A controlled trial (n = 70) of an occupational health education program was undertaken in rural Thailand prior to the occupational health education program. There were no differences in behavior between experimental and control groups. Completion of the program led to a significant improvement in safe working practices and in the amount of the metabolite. However, significant differences were noticed after participating in the occupational health education program on both safety behaviors and the amount of the metabolite 3,5,6-trichloro-2-pyridinol present in urine.