Abstract: New 2-[4-(diphenylmethyl)-1-piperazinyl]-acetic acids, their amides and their salts, processes for the preparation thereof and therapeutic compositions. These compounds have the formula ##STR1## wherein Y=--OH or --NH.sub.2 ; X and X'=H, halogen, alkoxy or trifluoromethyl; m=1 or 2 and n=1 or 2.The amides of the 2-[4-(diphenylmethyl)-1-piperazinyl]-acetic acids are prepared either by reacting a 1-(diphenylmethyl)-piperazine with an omegahaloacetamide, or by reacting an alkali metal salt of an omega-[4-(diphenylmethyl)-1-piperazinyl]-alkanol with a 2-haloacetamide, or yet by reacting ammonia with a halide or alkyl ester of a 2-[4-(diphenylmethyl)-1-piperazinyl]-acetic acid, whereas the 2-[4-(diphenylmethyl)-1-piperazinyl]-acetic acids are prepared by hydrolyzing the corresponding amide or lower alkyl ester.These compounds have in particular an antiallergic, spasmolytic and antihistaminic activity.