The Sykes-Moore and Rose chambers have been used for many years in time lapse studies of subconfluent cell cultures. Unfortunately, use of a Sykes-Moore chamber for the time lapse studies of cells maintained at very high cell density was found to be unsatisfactory even if a medium perfusion system was employed. First, CO2 produced by cells led to the formation of gas bubbles which often obstructed the optical path. Second, the specimen regularly went out of focus due to gas pressure build up which caused the top and bottom glass coverslips to warp and occasionally break. Third, after several days, cells underwent degenerative changes apparently due to lack of oxygen. A simple culture chamber is described here which permits cells to be maintained at very high cell density and observed at high magnification for a week or more.