Features of the casual search method application at MT sounding data interpretation in horizontal-layered media on modeling and practical examples are considered. Criteria of revealing missing layers in the initial approach are developed and the technique of the missed layer recovery is suggested. Testing the casual search method is performed on the practical data of MT sounding application for geothermal exploration in Kamchatka. The high accuracy of coincidence of the measured and calculated values of apparent resistivity and impedance phase and good correlation of interpretation results at various sounding stations is obtained.