In this study, determination of recharging mechanism of the Derme karst spring by hydrogeochemical analysis and environmental isotope techniques are aimed. The Derme karst spring is an important karst spring that is located in the eastern part of Turkey, meets the domestic water need of Malatya province having a population of 750000, and has an average flow rate of 2.7m(3)/s. Water samples were taken from eight different springs from May to October 2011 for physicochemical and isotopic analyses (oxygen 18, deuterium, tritium) in order to determine the catchment mechanisms and the hydrodynamic structures of these karstic springs. The hydrogeochemical classification of spring waters was performed through a piper diagram. The results indicated that all of the springs were characterized by the calcium bicarbonate type. It was found that the deuterium excess value of the karstic springs was ranging from 13.42 to 18.84%, and that these springs were fed by both territorial and marine origin rainfalls. It was considered that the springs in the karstic region were under the influence of different karstic systems.