Abstract: An apparatus for cultivating cells as disclosed includes a cell culture chamber having inlet and outlet ports, a substrate (7) with an anchorage surface for attachment of cells, and a system for circulating a culture medium in the cell culture chamber through the inlet and outlet ports. The medium circulating system cooperates with valves to control the surface level of the medium in order to submerge the anchorage surface in the culture medium and intermittently expose the substrate from the culture medium, thereby increasing the rate of gas exchange through a thin film of the culture medium formed on the anchorage surface. A method for cultivating cells by using the apparatus is also disclosed.