In this paper, we study the leader-following attitude consensus problem for multiple rigid body systems by a distributed unit quaternion-based attitude feedback control law. The control law is based on the certainty equivalence principle and contains a distributed observer for estimating the state of the leader and an auxiliary system compensating for the unavailability of the angular velocity. It is shown that the problem is solvable under the standard assumption that each follower can access the information from the leader through a directed path. (C) 2016 Elsevier Ltd. All rights reserved.