Recent advances in reliability methods, optimization as well as design sensitivity analysis have resulted in development of computational systems supporting reliability-based design optimization (RBDO) processes for medium/large structures. For RBDO the efficiency problems are critical and in order to get the optimum design a number of fast approximate methods have been recently proposed. These methods, tested for rather small problems, show acceptable accuracy and speed up computations considerably. However, when applied in the automated way to medium/large scale problems they may cause severe convergence problems or lead to a poor local minimum after expensive computations. Convergence problems are manifested in a specially severe way when stability of structures is under consideration. Instead of an automated optimization procedure, an interactive approach is proposed. Implemented in the POLSAP-RBO system, it allows to combine effective interactive design methods with visual capabilities to efficiently generate optimum design. The system allows to consider the local and global stability problems of truss structures. Interactive stability-oriented reliability optimization of an offshore jacket and truss-column is discussed in detail.