We have compared detailed planktonic and benthonic foraminiferal carbon and oxygen isotope records from the Palaeocene and early Eocene successions at DSDP Site 577 (Shatsky Rise, North Pacific), a composite section derived from DSDP Leg 74 sites (Walvis Ridge, South Atlantic) and a composite section from ODP Leg 113 sites (Maud Rise, Weddell Sea). The delta (super 13) C records of Palaeocene and early Eocene Foraminifera at Site 577 and the Leg 74 sites show that an increase in delta (super 13) C values in surface waters at 64 Ma (end of Zone P1) resulted in increased vertical carbon isotope gradients between surface and deeper dwelling planktonic foraminifera, and between surface-dwelling planktonics and benthonic foraminifera which became progressively steeper until the middle late Palaeocene. This steepening also occurs in the latest Palaeocene of the composite Leg 113 section and can be explained by an increase in surface ocean productivity. This increase in productivity probably resulted in an expansion of the oxygen minimum zone. (mod. journ. abst.)