1-Substituted-4-(1,2-diphenylethyl)piperazine derivatives of the formula: ##STR1## wherein X is 2- or 3-hydroxy, 2-methoxy, 3-methyl, 3-alkoxy having 1 to 4 carbon atoms, or 2- or 3-alkanoyloxy having 2 to 5 carbon atoms; R is allyl, 3-hydroxyisoamyl, 3-methyl-2-butenyl, 3-methyl-3-butenyl, propyl, an unsubstituted monocycloalkyl having 5 to 8 carbon atoms, 2-chlorophenyl, or a phenyl substituted by hydroxy or methoxy; with proviso that when X is a substituent at position 2, R is cyclohexyl and when X is 3-methyl, R is 2-methoxyphenyl or an unsubstituted monocycloalkyl having 6 to 8 carbon atoms, and their pharmaceutically acceptable salts, and the preparation thereof, and analgesic or antitussive compositions containing the same as the essentially active ingredient.