The present invention provides a process for preparing polycarboxylic acid imidazolines of the general formula: ##STR1## wherein X is --Cl, --OH, --O--SO.sub.3 H, --O--PO.sub.3 H.sub.2, --O--CH.sub.2 --CH.sub.2 --COOH, --NH.sub.2, --NHalk or --N(alk).sub.2, alk being an alkyl radical containing up to 6 carbon atoms, n is a whole number of from 2 to 4, R is a C.sub.8 -C.sub.18 hydrocarbon radical which is straight-chained, branched, saturated or one to three times unsaturated, m is a whole number of from 2 to 5, R' is a hydrogen atom or a carboxyl group and R" is a hydrogen atom or a methyl radical. In the process, a compound of the formula ##STR2## in which R, X and n are as defined above, is condensed with about a 2- to 5-fold excess of acrylic acid, methacrylic acid, maleic acid or a mixture thereof.