Values of δ18O in the ice veinlets of modern syngenetic ice wedges on Ayon Island, in northern Chukotka and on the neighboring islands of Eastern Arctic of Russia, according to (Vasil'chuk, 1992) with additions. Winter mean (twint.mean) and January (tJ) air temperature values were calculated using equation: tJ = 1.5 δ18Opiw (±3 °C), twint.mean = δ18Opiw (±2 °C). by the technique of Yu. Vasil'chuk (1989, 1991). Mean annual ground temperatures were calculated using reconstructions of mean summer temperature by the technique of A. Vasil'chuk [2007] and of mean winter temperature by the technique of Yu. Vasil'chuk (1989). Isotopic analyses were performed at the Institute of Water Problems, RAS and at the Institute of Geology, the city of Tallinn. Oxygen isotope measurements of ice wedge were carried out in the isotope laboratory of the Institute of Geology of Estonia (Prof. R. Vaikmae) using a Finnigan Delta-E mass spectrometer. Analytical precision was ±0.4‰ and in the isotope laboratory of the Institute of Water Problems RAS (Dr. A.Yesikov) using a Finnigan MAT 250 mass spectrometer. Analytical precision was ±0.6‰.