In this article, we describe a technique to determine dry snow grain size from opti- cal observations. The method is based on analysis of the snow reflectance in the near-infrared region, in particular, the Medium Resolution Imaging Spectrometer (MERIS) band at 865 nm, which is common to many spaceborne optical sensors, is used. In addition, the algorithm is applied to the Moderate Resolution Imaging Spectroradiometer (MODIS) 1240 nm band. It is found that bands located at 1020 and 1240 nm are the most suitable for snow grain size remote-sensing applica- tions. The developed method is validated using MODIS observations over flat snow deposited on a lake ice in Hokkaido, Japan.