ABSTRACT: The oil refinery SLOVNAFT, a. s. is situated upstream of Water Management Protected Area “Žitný ostrov”. Geological environment of this area is formed by alluvial sandy gravel deposits that are characterized by high hydraulic conductivity (up to n.10-2 m·s-1). The Groundwater Hydraulic Protection System (GWHP) SLOVNAFT, a. s. was created to protect the aquifer of Žitný ostrov area against contamination. Basis of the GWHP SLOVNAFT, a. s. is array of 20 remediation-pumping wells situated in eastern border of the refinery. Second important part of the GWHP is system of 47 (31. 12. 2016) pumping wells called Solowells that are located in a centres of confirmed polluted zones. GWHP and Solowells, by continual change of well yield, change the natural groundwater flow direction, prevent the transport of free and dissolved hydrocarbons outside the refinery area and are at the same time used for remediation of present contamination. Third part of the system is array of 695 monitoring wells situated in the refinery area and its surroundings. The results of qualitative and quantitative monitoring confirm proper function and necessity of the GWHP SLOVNAFT, a. s. system. Operation of GWHP system is performed in accordance with the Instruction of State Water Management authorities.