One of the main problems in induction motor (IM) control is the lack of knowledge about the actual value of the rotor resistance, which is often uncertain and subjected to variations during operation. Due to the unavailability of the rotor electrical quantities, it is not easy to define an output-error suitable to be used as "engine" for an identification mechanism. In the paper, two adaptive/variable-structure identifiers, based on different standing assumptions, are proposed. The high simplicity of the auxiliary system to implement and the low dimension of the associated regressors (to which correspond mild PE requirements) constitute the main novelty, and positive feature, of the proposed approach. Simulations results are provided at the end of the paper.