The kinetics of mammalian cell growth in a microcarrier culture are affected by the distribution of cells on microcarriers. It has been shown previously that a critical cell number per microcarrier is required for the growth of FS‐4 cells on microcarriers. It is advantageous to alter the cell distribution on microcarriers to allow for a larger fraction of microcarriers to acquire enough cells to initiate normal growth. This can be achieved by selecting the diameter of the microcarriers employed. It has also been shown previously that the critical cell number could be reduced by choosing a better culture medium to support low density growth. However, even if all cells inoculated into a culture are capable of growing to confluence, it is still necessary to select the microcarrier diameter ration ally to improve the growth kinetics. The method of selecting the microcarrier diameter is discussed. By employing a improved medium as well as using microcarriers of selected diameter, the multiplication ratio was in creased to 15‐ to 16‐fold for FS‐4 cells, as opposed to 3‐ to 4‐fold typically obtained in a batch culture.