This article presents the results obtained during a study of microlayer evaporation and ifs role in heat transfer during boiling in narrow slot channels. Experiments were run in a flat vertical channel. The distribution of microlayer thick-ness along the vertical radius was obtained from interferograms taken using a one-beam laser interferometer and high-speed photography. For the first time, the "nonevaporating" scenario of microlayer evolution, proposed by Moore and Mesler in 1961, was proved experimentally. Analytical examination of the microlayer formation process was carried out using the approach of Katto and Shoji, and laking into account the body force. The comparison of the results obtained, and published previously, is also presented in the article.