The present invention relates to a stable crystalline form of N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy)-4-quinazolinamine hydrochloride designated the B polymorph, its production in essentially pure form, and its use. The invention also relates to the pharmaceutical compositions containing the stable polymorph B form of N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy)-4-quinazolinamine as hydrochloride, as well as other forms of the compound, and to methods of treating hyperproliferative disorders, such as cancer, by administering the compound.