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Pellet casting was studied in a population of South Island robins (Petroica australis australis) at Kowhai Bush, Kaikoura from April 1977 to July 1978. Pellet regurgitation is described. Casting has a diurnal rhythm. Monthly regurgitation rates reflected the diet of the robins, with the highest rates occurring in the summer months when the main food is berries and invertebrates with their indigestible seeds and exoskeletons. It was calculated that, during February 1978, the month of highest mean egestion rate, a Robin would egest six pellets per day. The effect of age and sex on the frequency of castings is discussed.