New 4-acylaminophenylacetamidines of the formula: ##STR1## in which R is a straight or branched chain alkoxyalkyl having 3 to 8 carbon atoms or straight or branched chain alkenyloxyalkyl having 3 to 8 carbon atoms wherein the alkoxy moiety or alkenyloxy moiety may substituted by alkoxy or phenyl, and including the non-toxic pharmacologically acceptable salts thereof. The products have utility as parasiticides.The products are obtained by either of two methods: (1) via the reaction of an N'-(4-aminophenyl)-N,N-dimethylacetamidine with an acylating agent or (2) via the reaction of a 4-acylaminoaniline with an N,N-dimethylacetamide or N,N-dimethylthioacetamide.