The Purpose of the paper is development of the methodology for determining the volume of accessed and prepared reserves for complex structure ore deposits on example of the Golets Electricheskiy field. Methods. The study involves the following methods: analysis of existing concepts of prepared and accessed reserves, known methods of their determination, documentation rating the volumes of these reserves; analysis of mining and geological conditions of ore body occurrence in the complex structure ore field Golets Electricheskiy, deposit development technology and parameters; justification of the methodology for determining the volumes of prepared and accessed reserves. Results. The proposed methodology for determining the accessed and prepared reserves has been tested as applied to the conditions of the deposit Golets Electicheskiy. The optimal ratio of the lengths of excavating blocks for each of the horizons involved in simultaneous mining is determined. Conclusions. The length of excavating blocks on the horizons should be justified taking into account the specific operating conditions of the deposit, as well as the conditions of ore body occurrence. Since this paper takes the volumes of the prepared reserves according to the normative documents it is necessary to develop a methodology for determining the volumes of prepared reserves for each horizon involved in simultaneous mining.