New phenylsulphonamides of the formula in which ##STR1## R.sup.1 represents a pyridyl, quinolyl or isoquinolyl radical which is unsubstituted or substituted by halogen, alkyl, cycloalkyl, alkoxy, cyano, nitro, halogenoalkyl, halogenoalkoxy, alkoxycarbonyl or alkylsulphonyl,R.sup.2 represents hydrogen, cyano, nitro, halogen, alkyl, alkoxy, halogenoalkyl, halogenoalkoxy or alkoxycarbonyl,R.sup.3 represents an aryl radical which is unsubstituted or monosubstituted, disubstituted or trisubstituted by halogen, halogenoalkyl, halogenoalkoxy, alkyl, alkoxy, alkylthio, alkylsulphonyl, cyano, nitro or alkoxycarbonyl, the substitutents being identical or different, or represents pentafluorophenyl or represents a straight-chain, branched or cyclic alkyl which is unsubstituted or substituted by halogen, aryl, aryloxy, cyano, alkoxycarbonyl, alkoxy, alkylthio or trifluoromethyl, andX represents an --O--, --A--B-- or --B--A-- group, whereA denotes --O--, ##STR2## B denotes --O--; ##STR3## where R.sup.1 does not represent a pyridyl radical when X represents an --O-- group, and salts thereof are prepared by reacting appropriate amines with sulphonyl halides. The substituted phenylsulphonamides can be employed as active compounds for inhibiting enzymatic reactions and for inhibiting thrombocyte aggregations.