Despite studies on the distribution of Sr and Mg in shells of marine calcareous invertebrates, the question of possible seawater temperature control on the concentrations of these elements in carbonate material remains controversial. Some workers have shown that individuals of a species living in warmer waters are richer in Sr and Mg than those living in cooler waters^1–7. Others have found no such relationship^8–12. We report here in tests of two planktonic foraminiferal species that the Sr concentrations are strongly related to late Quaternary climatic oscillations. Mg concentrations also show correlations with palaeoclimate, but not consistently. Concentrations of these trace elements, especially of Sr, in planktonic foraminifera may, therefore, be valuable for analysing palaeoclimatic history.