The aim of the study is quantitative estimation of methane emissions in the area of St. Petersburg and its suburbs based on observations at the Voeikovo station. The approach is based on formulation and regularized solution of an inverse problem. The effect of methane accumulation in the nocturnal boundary layer is used by the formulation of the problem. The emission field is not homogeneous. The mean flux density on the urban territory is 1 ¿ 0.3 g km-2 s-1. The total methane flux from the urban territory and its suburbs is estimated to be 60 kT year-1. These emissions estimates refer to nighttime conditions in summer; they do not include emissions through tall chimneys. The proposed technique of data processing allows, in principal, for locating unknown sources of emissions. It is the first experience in getting emission estimates from the large industrial region in Russia on the basis of atmospheric measurements. This work shows that national statistical self-assessments of methane emissions can be verified using independent atmospheric measurements.