The use of drugs in domestic animals is dominated by considerations of cost-effectiveness and profitability. They are extensively used against coccidial infections of poultry where they are an important factor in intensive husbandry. Ionophore antibiotics, which dominate this field, may have applications in ruminants. Imidocarb is of therapeutic and prophylactic value against babesial infections anf there are new prospects for control of theileriasis. Effective drugs for the control of African trypanosomiasis are limited and attention is being given to alternative uses of available compounds.