Coiling directions in Globorotalia miotumida (planktic foraminifera) are reported from five sequences in New Zealand and the southwest Pacific Ocean between 31 degrees S and 40 degrees S. All show a well-defined zone (here termed the Kaiti coiling zone) near the base of the upper Miocene in which the long-term succession of sinistrally dominated populations is replaced by one or more intervals where dextrally coiled shells are in the majority. The zone is widespread in the region and occurs in neritic through oceanic sediments. Changes in dominant coiling direction are abrupt and local stratigraphic resolution is potentially high, (possibly 15 ky). The last occurrence of Paragloborotalia mayeri was near the base of the zone, which at DSDP Site 290B lies in the lower part of oxygen isotope Zone Mi6 and may have occurred during cool climatic conditions. However, comparison of coiling signatures with delta (super 18) O data and relative abundances of other planktic foraminifera does not identify any simple, consistent environmental relationship. It is suggested that coiling direction has some features of an evolutionary character.