This study presents new data derived from changes in benthic foraminiferal assemblages between 24 and 8 Ma in the Atlantic and Indian oceans which are integrated with published stable isotope and fauna1 records. We have identified an intermediate to deep water mass which was lower in oxygen and was restricted to the NW Indian, Atlantic and the Tethys (Mediterranean) oceans. Our interpretations are based on the coeval occurrences (19.5–16.5 Ma) of high abundances of smooth-walled bolivinids in these oceans. Our observations agree with the interpretations of previous workers for the occurrence of Tethys-derived intermediate and deep water in the northern Indian Ocean between 24 and 14 Ma and for Northern Component Water production in the Atlantic Ocean between 20 and 16 Ma. The water mass defined by these bolivinids formed a southward flowing Northern Component Water in the Atlantic Ocean and contributed, via Tethys, to the intermediate and deep water input into the Indian Ocean.