Knowledge of regional palaeohydrology is essential for understanding current environmental issues, such as the causes of recent hydrologic changes, impacts of land use strategies and effectiveness of wetland restoration measures. Even the interpretation of model results on future impacts of climatic and land-cover changes may be improved using (pre-)historic analogies. An overview of palaeohydrologic findings of the last c. 20,000 years is given for northeast Germany with its glacial landscapes of different age. River development is examined with a focus on valley(-floor) formation and depositional changes, river course and channel changes, and palaeodischarge/-floods. Major genetic differences exist among ‘old morainic’ (Elsterian, Saalian) and ‘young morainic’ (Weichselian) areas, and among topographically high- and low-lying valleys, the latter of which are strongly influenced by water-level changes in the North and Baltic Seas. Lake development was analysed with respect to lake formation, which was predominantly driven by late Pleistocene to early Holocene dead-ice dynamics, and with respect to depositional changes. Furthermore, lake-level changes have been in the focus, showing highly variable local records with some conformity. The overview on peatland development concentrated on phases of mire formation and on long-term groundwater dynamics. Close relationships between the development of rivers, lakes and peatlands existed particularly during the late Holocene by complex paludification processes in large river valleys. Until the late Holocene, regional hydrology was predominantly driven by climatic, geomorphic and nonanthropogenic biotic factors. Since the late Medieval times, human activities have strongly influenced the drainage pattern and the water cycle, for instance, by damming of rivers and lakes, construction of channels and dikes, and peatland cultivation. Indeed, the natural changes caused by long-term climatic and geomorphic processes have been exceeded by impacts resulting from short-term human actions in the last c. 50 years as discharge regulation, hydromelioration and formation of artificial lakes.