To understand the role of climate change in the extinction of Mammuthus primigenius in Eurasia, we examine spatial and temporal variations in growth increment and oxygen isotope (δ18O) profiles of radiocarbon dated mammoth tusks. We serially sampled tusk dentin in late Pleistocene tusks from the Taimyr Peninsula and Chukotka and Holocene tusks from Wrangel Island for a total of 241 oxygen isotope analyses from 11 tusks. Most sample series spanned 2-3 years of tusk growth. Differences in mean δ18O values among the Taimyr tusks correlate with δ18O values in corresponding intervals in the Greenland ice sheet and with regional paleoclimate reconstructions. The longitudinal gradient in δ18O values of late Pleistocene tusks (-0.064‰/degree) is similar to the modern meteoric water gradient (-0.064 to -0.048‰/degree). The temporal gradient in mean tusk δ18O in Taimyr from an interstadial during MIS 3 to a stadial during MIS 2 (4.0‰) is similar to the gradient in easternmost Siberia from an interstadial during MIS 3 to the middle Holocene (4.8‰). Seasonality in Chukotka during the late Pleistocene does not appear to be different from that on Wrangel Island during the Holocene. Our results suggest that climate change as recorded by δ18O values of mammoth tusks may not have been the direct cause of the extinction of Eurasian mammoths.