<p class="Normal1">The inherent relation between the instability parameters α and γz is studied in this paper. Such parameters are simplified criteria widely used in structural design in Brazil to evaluate the necessity to consider the global second order effects. Thus, an analytical relation between the parameters α and γz is proposed through a simple example. For this, design values of α and γz of thirty reinforced concrete buildings and twenty-two masonry buildings were used. The obtained results prove the accuracy of the proposed formulation for both types of construction</p>