The application of non-linear optimization procedures to the design of reinforced concrete buildings and prestressed concrete bridge decks is described. Attempts have been made to search for optima which are sufficiently accurate for practical purposes without using repeated structural analyses. This is particularly important when finite elements are used. Change of self-weight can influence the direction of search during optimization and this can be taken into account by including additional loading cases during intermittent structural analyses. It is concluded that such programs can be incorporated advantageously in future interactive design systems which use more powerful computers and graphical display units.