Abstract According to Hooke’s law the magnitude of infinitesimal elastic strains depends upon two independent constants. In this paper equations are developed which express the magnitude and the distribution of the strains in terms of two independent functions of the stresses. One function is related to the stress-strain diagram while the other is concerned with the distribution of the strains in a state of combined stress. The equations are easily adaptable to the relations between the strain rates and the stresses in combined stress-creep tests. It is the opinion of the author that two independent functions are necessary and that the behavior under a state of combined stress cannot be predicted from data obtained in pure-tension tests.