ABSTRACT Nine Planktonic foraminiferal datums proposed and utilized by Hays and others (1969) in their study of eastern equatorial Pacific Pliocene/Pleistocene sediments have been applied to the thick sections recovered in continuous coring of three Leg 9 Deep Sea Drilling Project (DSDP) sites in the same area. At best the datums based on dissolution susceptible foraminiferal species were found to be difficult to identify in the deep-water sediments. Datums based on coiling changes were found to be particularly reliable and easily recognized. Magnetostratigraphy within the Pliocene/Pleistocene interval presented by Hays and others (1969) was readily correlated with the DSDP cores by using foraminiferal datums. Average specimen size in assemblages of Pulleniatina primalis and P. obliquiloculata and faunal diversity of the planktonic foraminifera were both found to show relationships with coiling changes in these two species. Four new potentially reliable datums are proposed in the sequence and are based on coiling changes in Pulleniatina.