The East Rhodope Depression situated in South Bulgaria is a Paleogene superimposed structure. It is mostly filled with Tertiary sedimentary, sedimentary-volcanogenic, andvolcanic rocks. The tectonic low-order elements distinguished in it are specific volcanotectonic, block, and block-fold structures. The subjects of our study are the aquifer layers (reservoir systems) situated in these structures investigated from the point of view of the possibilities, if other favorable conditions for storage of natural gas and carbon dioxide (СО2) exist. Special studies carried out by the authors in the limits of the perspective structures are concentrated mostly on the: lithological-physical segmentation of the Tertiary section; defining of permeable and hard-permeable formations and their studying (structure, lithology, reservoir and sealing parameters, spatial behavior); defining of natural reservoirs and studying their spatial relationships; prognosis of possible types of local structures and natural traps. Because of the restricted volume and the absence of specialized information for a number of important geological preconditions and parameters, prognostic assessments are made with the use of indirect data, based on the contemporary ideas about the geological evolution of the examined region. Such are the structural-tectonic, the seismotectonic and the hydrogeological (hydrochemical, hydrodynamic) and the thermo-baric conditions. The prognoses concerning the perspectives for storage of natural gas and СО2 are related to the sunken areas within the Dzhebel and Krumovgrad depressions.