Abstract: A rack contains a number of shelves arranged on top of each other, which carry, among other things, board magazines with printed circuit boards. An apparatus for cooling the aforesaid printed circuit boards containing telecommunications or electronic equipment in each rack is based on the principle that one or more shelves in the rack are integrated each with its own heat exchanger, which is equipped with cooling flanges and at least one tubular coil. The heat exchanger is connected to a cooler for a coolant. The heat exchanger covers the greater part of the horizontal plane of the shelf. Heat-transfer members with extensive heat-conducting contact surfaces are provided between the board magazines and the body of the shelf and between the latter and the heat exchangers.