Compounds of formula (I), wherein G.sup.1 is CH or N; G.sup.2 is CH or N; R.sup.1 is a variety of optional substituents; L.sup.1 is (1-4C)alkylene; T.sup.1 is CH or N; R.sup.2 and R.sup.3 are independently hydrogen or (1-4C)alkyl or are joined to form a ring; X.sup.1 and X.sup.2 represent various linking groups; Ar is phenylene or certain heteroaryl rings and Q represents a variety of aromatic or heterocyclic rings systems, and pharmaceutically acceptable salts thereof are described as useful antithrombotic and anticoagulant agents, and are selective Factor Xa inhibitors. Processes for their preparation and pharmaceutical compositions containing them are also described. ##STR00001##