The structure of the crust and upper mantle of the Central Volcanic Region, New Zealand, are deduced from long-range seismic refraction and wide-angle seismic reflection data. Three shots were detonated in the Bay of Plenty and one in Lake Taupo; seismographs were located at approximately 10 km intervals between these shots. The geometry of the experiment was such that there was a partially reversed coverage for the crustal phases, but correlatable upper mantle phases were only recorded from the Bay of Plenty shots. A nondipping, plane-layer model to account for the refraction observations consists of a 15 ± 2 km thick crust of seismic velocity 5.5–6.15 km/s, underlain by an upper mantle with an anomalously low velocity of 7.5 ± 0.2 km/s. Wide-angle upper mantle reflections were also recorded from the Lake Taupo shot; a simple T2versus X2analysis of these reflections gives a depth of about 16±1 km to the upper mantle with a root-mean-square (r.m.s.) velocity for the crust of 5.94 ± 0.2 km/s.