Resumen en inglés

In the present work we introduce the concept of orthogonal frames in Krein spaces, prove the independence of the election of the fundamental symmetry, and from this we obtain a number of interesting properties that they satisfy. We show that there is no distinction between orthogonal frames in a Krein space and orthogonal frames in its associated Hilbert. In addition, we give some characterizations of frames in spaces of undefined metric, which is a useful tool for constructing new examples of frames.