The use of electron spin in future spintronic applications requires hybrid ferromagnetic/semiconductor structures with well controlled materials properties. Besides the control of the magnetic properties there are strict requirements for the material aspects of these devices: single phase, single crystal, perfect interfaces, defect control. Molecular beam epitaxy (MBE) has been used very successfully over the past 10 years to produce the most interesting spintronic heterostructures. In this paper we review our effort in using MBE to fabricate spintronic materials and heterostructures. We also discuss some aspects of future spintronic devices with the focus on the material aspects of transferring the electron spin information from the magnetic side of the heterostructure into the semiconductor side.