The layout of chemical facilities is an activity that is largely carried out by the human designer. Few methods exist for optimising layout. Difficulties in formulating the problem as a mathematical program stem from non-convexities as well as from non-differentiable cast functions. Recent attempts (Penteado and Chic, 1996) have succeeded in only implicitly including land costs, resulting in layouts which can be excessively conservative from the point of view of safety. The use of stochastic optimisation techniques, though not guaranteed to find the global optimum, has proved to be effective in obtaining good, practical solutions and permits the incorporation of more realistic cost functions and constraints. In this research, experiments were carried out using various genetic algorithm formulations, and the resulting program, which includes a useful graphical interactive component, is presented here.