PACS 73.20.-r -Electron states at surfaces and interfaces PACS 75.70.-i -Magnetic properties of thin films, surfaces, and interfaces PACS 78.20.-e -Optical properties of bulk materials and thin films Abstract -We present first-principles results for the electronic, magnetic, and optical properties of the BiFeO3/La 2 3 Sr 1 3 MnO3 heterostructure as obtained by spin-polarized calculations using density functional theory. The electronic states of the heterostructure are compared to those of the bulk compounds. Structural relaxation turns out to have only a minor impact on the chemical bonding, even though the oxygen octahedra in La 2 3 Sr 1 3MnO3 develop some distortions due to the interface strain. While a small charge transfer affects the heterointerfaces, our results demonstrate that the half-metallic character of La 2 3 Sr 1 3 MnO3 is fully maintained.