The present invention discloses substituted fused pyrimidine compounds of formula (I), their tautomers, polymorphs, stereoisomers, solvates, pharmaceutically acceptable salts, or pharmaceutical compositions containing them and methods of treating conditions and diseases that are mediated by adenosine receptor (AR) activity. The compounds of the present invention are useful in the treatment, prevention or suppression of diseases and disorders that may be susceptible to improvement by antagonism of the adenosine receptor, such as asthma, chronic obstructive pulmonary disorder, angiogenesis, pulmonary fibrosis, emphysema, allergic diseases, inflammation, reperfusion injury, myocardial ischemia, atherosclerosis, hypertension, congestive heart failure, retinopathy, diabetes mellitus, obesity, inflammatory gastrointestinal tract disorders, and / or autoimmune diseases.