Abstract: Insect repellants having improved effectiveness, increased mucosa tolerance and compatibility with plastic objects containing, as an active ingredient, at least one 3-aminopropionic acid derivative which is disubstituted at the nitrogen atom, having the general structure ##STR1## in which R.sub.1 is a branched or unbranched alkyl radical having one to six carbon atoms, R.sub.2 is hydrogen, methyl or ethyl, R.sub.3 is a branched or unbranched alkyl or alkoxy group having one to eight carbon atoms, and X is --C.tbd.N or --COOR.sub.4, R.sub.4 being a branched or unbranched alkyl group having one to six carbon atoms.