Phenoxyalkylcarboxylic acid compounds of the formula ##STR1## wherein R is hydrogen or lower alkylR.sub.1 is alkyl or aryl, aralkyl or aralkenyl radical, the aryl moiety of which can be substituted one or more times by halogen, hydroxyl, trifluoromethyl or lower alkyl, alkoxy or acylR.sub.2 and R.sub.3 are individually selected from hydrogen or lower alkyl, andn is 0, 1, 2 or 3and the physiologically acceptable salts, esters and amides thereof; are outstandingly effective in inhibiting thrombocyte aggregation.