It is well recognized that security is vital for the reliable operation of vehicular ad hoc networks (VANETs). One of the critical security issues is the revocation of misbehaving vehicles, which is essential for the prevention of malicious vehicles from jeopardizing the safety of other vehicles. In this paper, we propose an efficient decentralized revocation (EDR) protocol based on a novel pairing-based threshold scheme and a probabilistic key distribution technique. Because of the decentralized nature of the EDR protocol, it enables a group of legitimate vehicles to perform fast revocation of a nearby misbehaving vehicle. Consequently, the EDR protocol improves the safety levels in VANETs as it diminishes the revocation vulnerability window existing in conventional certificate revocation lists (CRLs). By conducting detailed performance evaluation, the EDR protocol is demonstrated to be reliable, efficient, and scalable.