Abstract: Amidinonaphthyl furancarboxylate derivatives of the formula I ##STR1## wherein A is a single bond or A denotes (a) a phenyl group, cyclopentyl group, or cyclohexyl group,(b) an alkenylphenyl group, alkylphenyl group, phenylalkenyl group, or phenylalkyl group wherein alkyl is C.sub.1 to C.sub.7 alkyl and alkenyl is C.sub.2 to C.sub.7 alkenyl,(c) a C.sub.1 to C.sub.18 alkyl or C.sub.2 to C.sub.7 alkenyl group which may be substituted by one or two substituents selected from C.sub.1 to C.sub.5 alkyl groups and quanidino groups, wherein an alkyl substituent together with the carbon atom to which it is attached may form a cycloalkyl ring having from 3 to 6 carbon atoms, or said C.sub.1 to C.sub.5 alkyl may itself be substituted by a C.sub.3 to C.sub.6 cycloalkyl ring, or(d) --(CH.sub.2).sub.n --NH--CO--(CH.sub.2).sub.n' wherein n and n' may be the same or different and represent an integer from 1 to 4; andwherein R denotes(e) a hydroxyl group,(f) a C.sub.1 to C.sub.