The applicability of a biological model, based on genetic evolution, is presented for the multiobjective optimization of engineering systems. Algorithms embodying the ideas of reproduction, crossover and mutation are developed for the solution of different types of multiobjective optimization problems. Both continuous and mixed variable optimization problems are considered. The design of a truss structure for minimum weight, minimum deflection and maximum fundamental frequency of vibration is considered with constraints on the induced stresses and bounds on the cross sectional areas of its members to demonstrate application to a continuous-variable problem. The structural design along with selection of actuator locations in an actively controlled structure, for minimum energy dissipation and minimum weight, is considered to illustrate application to a mixed-variable problem.