The limnological conditions of water bodies in the endorheic Uvs Nuur basin (Mongolian Altai) are described in this volume. The whole range is represented: rivers, lakes (fresh, saline) and springs/subsurface waters. The extreme gradients of altitude and climate (from glaciers to semidesert) characterizing the basin are reflected by the very different types of waterbodies, which are described exemplarily. Climatic conditions (precipitation, temperature, evaporation) as well as morphological (morphometry, substrate), hydrological (runoff, lake level changes, water age), physical (temperature, turbidity, conductivity), chemical (main ions, nutrients) and biological properties (benthos, plankton, chlorophyll) are presented. Since the area is remote and only sparsely populated, there are, as a rule, only minor anthropogenic influences on the morphology of the waters while the nutrient budgets are more affected due to the relatively dense livestock.