In the area of secure communications, key agreement is one of the most important issues. In this paper, a practical two-party ID-based authenticated key agreement protocol is proposed, which uses pairings on certain elliptic curves. An important advantage of our protocol is that it provides unilateral key confirmation to the protocol initiator only in two passes. We first put forward a variant of the ID-based signature scheme due to Sakai et al., then we describe our protocol, which uses the variant as a building block. We show that the newly proposed key agreement protocol is fit for real-world applications, and at the same time, it satisfies every desired security requirements of key agreement protocols.