A method is described by which the stress‐strain curve of a wire tensile specimen can be derived from measurements of its changes of electrical resistance as a function of strain. The method can be applied only to a selected group of metals that have experimentally been shown to be suitable. A material is suitable when its resistance changes per unit of elastic and per unit of plastic strain are each constant and different from each other. The method assumes uniform strain throughout the length of the specimen, which limits conditions studied to those prior to necking. Examples are shown illustrating the linear resistance‐strain relations and the applications of the method for several suitable materials. The resistance‐strain characteristics of several materials that are not suitable are given, together with a statement of some mechanisms responsible.