Stable oxygen isotopes composition (δ¹⁸O) in modern syngenetic ice wedges (recent ice veinlets - i.e. modern ice veins formed during the last 60-100 years and penetrated into older Holocene syngenetic ice wedges). 1. Stable isotope ratios (δ¹⁸O and δ²H) were analyzed at the stable isotope laboratory of the Faculty of Geography in the Lomonosov Moscow State University (headed by Prof. Yu. Vasil'chuk) using a Finnigan Delta‐V Plus mass spectrometer applying equilibration techniques. The values are presented in δ‐notation in per mil (‰) relative to the Vienna Standard Mean Ocean Water (VSMOW) expressed in per mil (‰). Analytical precision was ±0.1‰ for δ18О and±0.8‰ for δ2H. Oxygen isotope measurements of wedge ice sampled in 1987 were carried out in the isotope laboratory of the Institute of Geology of Estonia (headed by Prof. R. Vaikmäe) using a Finnigan Delta‐E mass spectrometer. Analytical precision was ±0.4‰. 2.Winter mean (twint.mean) and January (tJ) air temperature values were calculated using equation: tJ = 1.5 δ18Oiw (±3 °C), twint.mean = δ¹⁸Oiw (±2 °C) by the technique of Yu. Vasil'chuk (1989, 1991).