A circuit for cooling exhaust gas being recirculated through an EGR system (36) of an engine (10) from an exhaust system (20) successively through first and second heat exchangers (38, 40) to an intake system (16) for entrainment with intake air. Each heat exchanger has a respective coolant inlet through which liquid coolant enters and a respective coolant outlet through which liquid coolant exits after having absorbed heat from recirculated exhaust gas. The circuit has a third heat exchanger (32) to which coolant coming from the outlet of one of the first and second heat exchangers rejects heat, and parallel branches (84, 86) through which coolant enters the inlet of the other of the first and second heat exchangers. One of the parallel branches has a fourth heat exchanger (34) to which coolant flowing through that branch rejects heat, and one or more devices (50, 50A) for controlling the quantity of coolant flowing through each branch.