This invention pertains to diaminopyrimidine compounds having activity as antagonists of P2X purinergic receptors and to methods for treatment of diseases associated with P2X receptors comprising administering an effective amount of a diaminopyrimidine compound. More particularly methods are provided for using P2X3 and/or P2X2/3 antagonists in the treatment of cough chronic cough and urge to cough in respiratory conditions and disorders.