A. Bouzouina Stability of the 2D Brown-Ravenhall operator (33K, LaTeX) ABSTRACT. We prove that the two-dimensional Brown-Ravenhall operator is bounded from below when the coupling constant is below a specified critical value --- property also referred to as stability. As a consequence, the operator is then self-adjoint. The proof is based on the strategy followed by Lieb and Yau [LY] and by Evans, Perry and Siedentop [EPS] with some relevant changes characteristic of the dimension. Our analysis also yields a sharp Kato inequality.