Heat exchanger having a block of flat tubes arranged parallel to one another and having fins arranged between the flat tubes, wherein the flat tubes form flow ducts through which a refrigerant can flow, and a coolant can flow around the flat tubes, wherein the flat tubes are in fluid communication, at end regions, with collecting tanks, wherein the refrigerant can be made to flow into an inflow region of a collecting tank in fluid communication with at least one of the flow ducts, wherein the inflow region has a line, which extends through the inflow region, for inflow of the refrigerant, wherein a refrigerant passage is provided from the line to the collecting tank inflow region, said refrigerant passage arranged in the central region of the collecting take inflow region, wherein the central region is in relation to a direction oriented perpendicularly to a plane of the flat tubes.