In 2001, world pesticide use exceeded five billion pounds, with a value of about US$32 billion. The many hundreds of agricultural chemicals, like pharmaceuticals, have evolved rapidly since the mid-20th century toward improved specificity, efficacy, and safety profiles. Current generation herbicides and fungicides are, of course, not designed to be active in animals. Consequently, with a few notable exceptions, animal toxicity is only observed at very high doses. Insecticides and rodenticides generally present a much greater danger to non-target animal species, including humans. This chapter covers the toxicologic pathology profiles of four major classes of agricultural chemicals: herbicides, fungicides, insecticides, and rodenticides. In these limited pages we discuss a handful of pesticides within each class; materials that were chosen for their wide usage, diverse mechanisms, and often interesting toxicological profiles, and, occasionally, for their historical importance. Information on the sources, toxicology, pathology, and human risk as well as the diagnosis, treatment, and prevention of significant unintended exposure is briefly synopsized for each selected chemical. A generous reference section will lead the curious into oceans of further reading.