The bio-efficacy of a cereal-based bait formulated with two acute rodenticides, fluoroacetamide and zinc phosphide and two second generation anticoagulants, bromodialone and difethialone at different concentrations was evaluated against laboratory-bred wild type rats, Rattus rattus. Bait containing 2% fluoroacetamide and incorporating edible green colour 0.025% and human feeding deterrent denatonium benzoate 0.001% produced complete mortality in 6d and was considered to be the most effective. (C) 2002 Elsevier Science Ltd. All rights reserved.