Twelve upper Pliocene‐lower Pleistocene calcareous nannofossil events are calibrated with oxygen isotope stratigraphy at eight DSDP/ODP sites ranging from 53°N to 41°S latitudes in different oceans in order to determine their ages and to reveal their synchrony or diachrony within a significantly higher‐resolution time scale than the geomagnetic polarity time scale allows. Six nannofossil events appear to be synchronous from low to middle latitudes (the last occurrences ofReticulofenestra asanoi(oxygen isotope stage 22),Gephyrocapsaspp. A‐B (stage 37),Discoaster brouweri(stage 71),Discoaster surculus(stage 99),Discoaster tamalis(stage 111), and the first occurrence ofGephyrocapsaspp. A‐B (stage 59)), five appear to be diachronous (the first occurrences ofGephyrocapsaspp. C‐D,Reticulofenestra asanoi, andGephyrocapsaspp. A‐B larger than 5.5 µm, and the last occurrences ofHelicosphaera selliiandDiscoaster pentaradiatus), and one is synchronous at low latitudes (the last occurrence ofCalcidisc