Compounds of formula (I) i.e. monocyclic or bicyclic diamine-substituted thieno[2,3-d]pyrimidine and isothiazolo[5,4-d]pyrimidine derivatives substituted by an optionally substituted oxazolin-2-yl moiety, are beneficial in the treatment and/or prevention of various human ailments, including inflammatory, autoimmune and oncological disorders; viral diseases; and organ and cell transplant rejection.