Many of the climate change researchers believe that in this century the average temperature is expected to rise apart from the climate becoming more extreme (Solomon et al., 2007). These weather anomalies can significantly influence the living beings, including the range limits of plants. This could seriously effect our indigenous tree species, some prognoses assume that the 82-100 % of the zonal spread of the sessile oak will have fallen outside the optimum climate area in tthe Carpathian Basin by 2050 (Czúcz et al., 2013). Such and similar forecast make the climate tolerance and health condition examinations of the sessile oak stands particularly important, so that we can measure the changes in plant communities. We have examined the health conditions of two elderly - over the age of 100 years - stands with the FAKOPP +D Acoustic Tomograph. One of the stands can be found in the Börzsöny Mountain, s while the other one in the Gödöllő Hills.