ABSTRACT: The present paper gives a brief overview of definitions and understandings of storativity coefficients, specific yield and porosity, and its relation to the way of testing and interpretation. The main differences in understanding of these parameters are also characterized according to information found in literature written both in Slovak and in English. These hydraulic parameters are material physical properties that characterize the capacity of an aquifer to store and release groundwater from storage in response to a hydraulic head variation. For that reason they are sometimes referred to as “storage” or “natural capacity” properties. In the field of hydrogeology, these properties are often determined by combination of field hydraulic tests (e.g., aquifer tests) and laboratory tests on aquifer material samples. An overview of accessible data for storativity and specific yield found in Slovak and international literature listed in tabular form is an inherent part of the paper, as it contains the main source of information available especially from the Slovak territory. The collected data are very heterogeneous, what has to be taken on account when interpreting them. The rock types are divided into groups, based on lithology. An attempt to gather data on water-table storativity, derived from aquifer tests performed on the Slovak territory, showed that very few reports contain such values. Data of storativity coefficient for many typical rock types from Western Carpathians are still missing.