The densities of 800 rock samples representing the major sedimentary, metamorphic, and igneous formations in New Zealand are summarised and tabulated. The youngest Pleistocene rocks have a wet density of l-88g/cm3, and this increases down through the Tertiary column to 2-55g/cm3 in the Cretaceous. Jurassic-Permian greywackes have a wet density of 2-65g/cm3 and the oldest sediments a wet density of 2-68 g/cm3. Metamorphosed rocks have higher densities. The greatest anomaly in the igneous rock densities is the very low value (2-18g/cm3) for the rhyolites of the Rotorua thermal area.