Devices themselves are the network in ad hoc networks allowing seamless communication, at low cost, in a self-organized fashion and also easy deployment. Freedom and self-organizing capabilities make Mobile Ad hoc NETworks (MANETs) completely different from other networking solution. MANETs highly dynamic nature leads to changes and network topologies unpredictability, adding difficulty and complexity to mobile node routing within the network. This study proposes a new, secure, Dynamic Source Routing (DSR) protocol for MANETs based on trust and reputation to mitigate black hole attack.