It is known that the deflection of a diaphragm is determined by two mechanisms, bending moments or bending stress and tensile forces or membrane stress. Usually the influence of tensile forces is not taken into account when calculating the mechanical properties of thin diaphragms. Hence the mathematical description thus obtained will only be valid if the deflection of the diaphragm is small compared with its thickness and if lateral stress is absent. In this paper we will consider uniformly loaded circular diaphragms, which are assumed to be isotropic, and present the results of a study on the influence of bending stress and tensile stress, which together determine the diaphragm deflection. Starting from theoretical considerations, a simulation program is developed of which several results are presented and discussed.