The invention relates to 3-aryl-5-alkoxy-pyrazoles, represented by general formula (I): ##STR1## wherein Ar represents an aryl group which may be substituted; R represents a hydrogen atom or an alkyl, phenyl or benzyl group; R.sub.1 and R.sub.2 which may be the same or different, each represent a hydrogen atom or an alkyl group, or together form a 5 or 7 membered heterocyclic ring with the nitrogen atom to which they are attached; and n is an integer of from 1 to 4; and the pharmaceutically acceptable acid salts thereof, useful in particular, in the treatment of cardiac arrhythmias.