MANET is used by many researchers to provide security and to implement protocols for secure routing. Privacy and security are important in applications like Military and Law-Enforcement MANETs. Communication in MANET is more susceptible due to broadcasting nature of radio transmission. It is necessary to provide security against inside and outside adversaries. There are many existing schemes which provide privacy preserving routing. These schemes do not offer complete unlink ability and unobservability. We propose unobservable secure routing protocol where data packets and control packets are completely protected. It achieves content unobservability by applying group signature and ID-based encryption. This protocol works in two stages anonymous key establishment and unobservable route discovery. We implement unobservable secure routing protocol with security algorithms RSA, AES, DES with AODV in NS-2 and compare it with AODV. Our protocol is more efficient than existing schemes. © 2015 IEEE.