A detailed study of the 3D variation of shear-wave velocities in the southern part of the Korean Peninsula is made by combining high-frequency surface- wave tomography results of Cho et al. (2006b) with teleseismic P-wave receiver functions at 80 locations on the peninsula. Receiver functions were derived from high-gain acceleration, short-period, and broadband digital data streams of the Korea Meteorological Administration (kma) and Korean Institute for Geosciences and Mineral Resources (kigam) networks. Vertical cross sections trace the lateral variation in the depth to the Moho, the variation of low velocities near the surface, and the variable thickness of the transition from surface velocities to midcrustal velocities. The derived crustal structure provides new insights on the evolution of the Korean crust.