The cation in (1R,2R)- 1,2-diphenyl- 1,2-ethanediamine monohydrobromide has approximate twofold symmetry and is involved in a three-dimensional hydrogen-bond network with the bromide anion [H...Br 2.51 (4)-2.82(3), N...Br 3.279(2)-3.560(3) A]. Principal bond lengths include Csp3--Csp 3 1.535(4), Csp3--NH~ 1.489(3), Csp3--NH2 1.469(4), and Csp3--Car 1.517(3) and 1.528(3) A. The main torsion angles defining the conformation are NH~--Csp3--Csp3--NH2 -44.3(2) and Car--Csp3--Csp3--Car 64.3(2) °. The absolute stereochemistry (known on chemical grounds) was confirmed by the analysis.