Novel analogues of mandipropamid have been designed and prepared. The synthetic approach to these stretched and heterocyclic mandelamides is outlined. Biological data demonstrate their high efficacy against important plant diseases like tomato and potato late blight (Phytophthora infestans De Bary) and grape downy mildew (Plasmopara viticola Berliner & de Toni). Structure-activity relationship studies are discussed.Copyright (c) 2006 Society of Chemical Industry.