In this work, we studying changes in the vegetation of floodplain forests of the Eastern Slovak lowlands caused by the modification of the water regime. Vegetation changes were evaluated on the basis of data obtained from the restoration of typological representative plots set up 50 years ago in the Latorica and Laborec basins. The fieldwork methods we used were the same as in the past. We used Juice and Microsoft Excel to process data. Using the Juice program, we created a combined synoptic table, which we analyzed the species that died, worsened, or did not change. We have also carried out an ecological analysis of plant communities to find changes in phytocoenosis claims on environmental properties. During data processing, we have created tables and charts for the surveyed territory. Subsequently, we divided the territory into two parts, namely the area between the river Latorica and Laborec and the flood dam, the second part representing the area behind the flood dam. This step was taken to better interpret changes in phytocoenoses. In the discussion, our data was confronted with the authors who were dealing with similar changes in vegetation. The evaluation of our research was captured in the chapter Conclusion.