A record of estimated sea surface temperature (SST) change between 575 and 400 ka has been obtained from planktonic foraminifera at Deep Sea Drilling Project Site 594 in the southwest Pacific Ocean. The Site 594 record indicates that SSTs during marine oxygen isotope stage 11 were similar to those of the Holocene, in contrast to suggestions of warmer than Holocene SSTs during stage 11. If these SSTs reflect global conditions, then ice-sheet collapse may not require temperatures warmer than in the Holocene. Millennial-scale oscillations in SST (∼3 °C) occurred within the stage 12 glacial interval, spaced every ∼5–10 k.y., on time scales similar to those observed within stage 12 in the North Atlantic. The consistency between these records may require global-scale mechanisms capable of producing rapid climate change, as suggested for later Quaternary intervals.