The European Aeronautics Industry’s Strategic Research Agenda addresses the reduction in operating costs of relevant European aerospace products by 15% through the cost effective application of carbon fiber composites to aircraft primary structure and taking into account systems integration. This can be achieved by realizing the weight saving potential of advanced composite materials, by reducing the manufacturing costs of composite components and by reducing subsequent product maintenance costs. Due to increasing application of advanced composites in aircraft structures, a significant progress was achieved recently in the buckling and post-buckling analyses of stiffened laminated composite panels. Since a weight reduction is the final purpose of utilization of composite materials in aerospace structures, some optimisation methodologies were developed too based on the response surface technique or using Genetic Algorithms. It is necessary to note that most developed approaches relate to the design of primary fiber composite fuselage structures without an evaluation of the effect of rib attachment to stiffener webs. This is why the present investigations are devoted to the optimisation of stiffened composite panels used as lateral wing upper covers and taking into account the effect of rib attachment to stiffener webs in terms of buckling behaviour.