In the European Union, coccidiostats and related compounds such as histomonostats which are given to animals in feed are regulated as feed additives rather than as veterinary medicinal products. Nevertheless, they are evaluated for safety in a similar manner to veterinary medicines and are subject to evaluation for consumer and user safety. The major groups used for these purposes comprise the ionophoric polyether compounds typified by lasalocid, monensin and maduramycin, and the non-ionophoric compounds such as amprolium, decoquinate and diclazuril. The toxicity of the compounds is reviewed in this chapter, along with the implications for consumer and user safety.