Groundwater tritium and helium isotope measurements were used to estimate the natural groundwater recharge at a Hungarian test site (Méntelek), which is a typical recharge area in the middle of the Great Hungarian Plain. As a first step, a previous groundwater tritium profile at 11 different levels of a 24 m deep borehole measured in the test site in 1998 was re-evaluated. A hydrodynamic and transport model assuming nearly vertical flow was created and calibrated by the measured tritium profile resulting 50 mm/year average groundwater recharge and 0.3 m dispersivity for the time period between 1951 and 1998. A new tritium and ³He profile at four different depths in a well nest developed in the described borehole was also measured in 2010. The average infiltration rate for 1951 to 2010 was calculated by new tritium data as 70 mm/year using the same models. ³H/³He ages are linearly growing via depth resulting in 0.32 m/year vertical flow velocity and 64 mm/year infiltration rate. Based on these results, a new simulation has confirmed that significant alteration in groundwater recharge between 1998 and 2010 could not be detected although it had been assumed by earlier climate change information.