The paper deals with the history of the development of methods used for the prognostic evaluation of hydrocarbon resources in the USSR, their modern classification, and the calculation techniques involved. Ultimate resources are divided into discovered reserves and predicted resources. The latter are divided into D1and D2sub‐groups, according to the presence or absence of production from the formation under evaluation. Prognostic resources include identified and unidentified components. The modern system of forecasting provides a review of adequate information and the determination of requirements for: (i) the quality of prediction; (ii) the creation of theoretical models for oil and gas generation and accumulation processes in the region under evaluation; (iii) the determination of quantitative functional relations as a forecasting tool; (iv) resources estimation using different models; and (v) the correlation of the results obtained and the differentiation of the resources in terms of the efficiency of capital investment required for their developmen