In this paper, we analytically compare IP versus AAL2/ATM as a transport technology in the UMTS Terrestrial Radio Access Network (UTRAN), where stringent delay bounds are to be met for both real-time and non real-time traffic. We particularly select voice and Web traffic so as to illustrate our investigation. We show that, for the case of voice traffic, AAL2/ATM has a small advantage over IP, in terms of delay; IP is however more efficient than AAL2/ATM in terms of link utilization, especially for heavy loaded systems. As of data traffic, IP performs best. q 2004 Elsevier B.V. All rights reserved.