In this paper four cases where displacement ventilation has been used in relatively large spaces are reviewed. In the first three cases measurements have been made of the temperatures, C02 concentrations (as an indicator of the air quality), efficiencies, and thermal comfort. In the fourth case numerical calculations have been made. In all the buildings studied the air is supplied directly to the occupied zone with low velocity either from inlets under the chairs or along the wafts, and extracted through openings dose to the ceiling. All the premises have a similar geometry to an amphitheater. The results show that the air quality and temperature efficiency for most of the space are better than that obtainable with a complete mixing system. The only exception is the C02 concentration and temperature at the back part of the premises, which are higher than the rest of the room. Each displacement ventilation system also seems to give satisfactory thermal comfort. Since the premises are relatively large, with the heat sources distributed across the floor, the results should be used with care when discussing other kinds of rooms.