A connection device for a heat exchanger between a first fluid (L) and a second fluid (G), said device comprising a connector (30) and a lateral end panel (37) of a heat exchange bundle (14) of said exchanger, said lateral panel (37) including at least one connection element (38) comprising transversely aligned inlet/outlet openings (47, 47′), said connection element (38) allowing the first fluid to flow between the bundle and the inlet and outlet openings (34, 36) of the connector (30), aligned longitudinally or at an angle relative to said inlet/outlet openings (47, 47′) of the connection element (38), said connection element (38) and said connector (30) being of substantially the same length.