The present disclosure relates to salts and compositions of isophosphoramide mustard and isophosphoramide mustard analogs. In one embodiment the salts can be represented by the formula ##STR00001## wherein A.sup.+ represents an ammonium species selected from the protonated (conjugate acid) or quaternary forms of aliphatic amines and aromatic amines, including basic amino acids, heterocyclic amines, substituted and unsubstituted pyridines, guanidines and amidines; and X and Y independently represent leaving groups. Also disclosed herein are methods for making such compounds and formulating pharmaceutical compositions thereof. Methods for administering the disclosed compounds to subjects, particularly to treat hyperproliferative disorders, also are disclosed.