This Chapter is a review of the computer simulations of surfactant systems. The focus is on monolayers and on micelles as relatively simple examples of surfactant self assemblies. During the last decade simulations of monolayers have progressed to a level of sophistication where they can be used to interpret experimental data and even suggest new experiments. The computer simulation of micelles is much less advanced. We demonstrate that simulations of micelles are much more difficult then those of the corresponding monolayers, and we present some very simple models that are able to describe a micellar solution.