In a proxy signature scheme, an original signer delegates her signing capability to a proxy signer who generates a signature on message on behalf of the original signer. By the combination of a blind signature with a proxy signature, the proxy signer can produce a proxy blind signature on message. Identity-based public key cryptosystem has an efficient key management as compared with certificate-based public key settings. In this paper, we propose an efficient identity-based pairing-free proxy blind signature scheme. The proxy blind signature scheme is provably secure upon the discrete logarithm assumptions in the random oracle model. Compared with other proxy blind signature schemes in the literature, the proposed proxy blind signature scheme is more efficient. Copyright © 2012 John Wiley & Sons, Ltd.