The interplay of electron-electron interactions and spin-orbit coupling has been the subject of much debate recently. On the one hand, spin-orbit coupling is at the heart of novel materials such as topological insulators and superconductors as well as Dirac and Weyl semimetals. On the other hand, interactions lead to many-body states responsible for ferromagnetism, ferroelectricity and superconductivity. It is quite likely, therefore, that interactions give rise to exotic phases in strongly spin-orbit coupled systems. In this talk, I will discuss possible effects of electron-electron interactions in systems with strong spin-orbit coupling, focussing on topological insulators and electron- and hole-doped semiconductors.