Airborne measurements of atmospheric methane (CH4) over oil fields in western Siberia were carried out on August 1, 1994. Extremely sharp CH4 peaks were observed in the horizontal distribution of CH4 at an altitude of 150 m above the ground surface; the half widths of the peaks were 3–4 km and the concentration of the largest peak exceeded 2.9 ppmv. Since the CH4 distribution was considered to reflect the distribution of CH4 emission strength on the surface, there was strong CH4 emission at the peak positions. All of the observed CH4 peak positions were located at or near oil production sites and/or oil pipelines, suggesting that natural gas was emitted from the facilities. Leakage or venting of natural gas are the probable CH4 sources.