Reliability based design optimization (RBDO) problems are important in engineering applications, but it is challenging to solve such problems. In this study, a new resolution method based on the directional Bat Algorithm (dBA) is presented. To overcome the difficulties in the evaluations of probabilistic constraints, the reliable design space concept has been applied to convert the yielded stochastic constrained optimization problem from the RBDO formulation into a deterministic constrained optimization problem. In addition, the constraint handling technique has also been introduced to the dBA so that the algorithm can solve constrained optimization problem effectively. The new method has been applied to several engineering problems and the results show that the new method can solve different varieties of RBDO problems efficiently. In fact, the obtained solutions are consistent with the best results in the literature. Citation details: A. Chakri, X.-S. Yang, R. Khelif, M. Becouaret, Reliability based design optimization using the directional bat algorithm, Neural Computing and Applications, First published online, 2017. https://doi.org/10.1007/s00521-016-2797-3 3the time delay between the two ears, they can create a 3D mental image of their surrounding and determine if there is food or not. This behavior was the basic idea that has been used to develop the bat algorithm. Several studies showed that BA can solve optimization problems with higher efficiency compared to standard algorithms such as .Despite the fact that BA is a powerful optimization algorithm, it may suffer from the premature convergence that can occur under certain conditions, which is also true for all other algorithms such as PSO and GA. To overcome this problem, several techniques have been proposed to increase the exploitation and exploration capability of the algorithm. In [23], the authors proposed to use simulated annealing and Gaussian perturbation to speed up the convergence rate. In [24], the authors suggested to use chaotic maps to control the pulse rate and loudness. In [25], the authors recommended to use the Lévy flights and the differential operator to generate the bats ' movements and, in [26], the authors proposed to consider the bats' habitat selection and their self-adaptive compensation for the Doppler effect in the algorithm formulation. Other studies suggested hybridization between the standard BA and classical algorithm such as PSO [27], Artificial Bee Colony (ABC) [28], differential evolution [29,30] and Invasive Weed Optimization (IWO) [31].