Blended Wing Body (BWB) Aircraft has aroused a considerable interest as a potential candidate for future large subsonic transport air-vehicles. In this paper, we present the results of one and multi-point multi-constrained optimization of a BWB configuration for minimum total drag. The optimization technique is based on Genetic Algorithms and is driven by full Navier-Stokes computations. The results show that the proposed technology allows the design of feasible aerodynamic shapes which possess a low drag at cruise conditions, satisfy a large number of constraints and offer good off-design performance at markedly different flight conditions.