The water chemistry of mountain lakes and its change in time is affected by variation in atmospheric deposition and climate. Climate warming is proved to be particularly pronounced in the Alpine region. It may affect both quantity and quality of water in mountain areas. The effects of climate warming on mountain lakes are mainly indirect, and result from a combination of multiple stressors. Temperature increase may enhance biological processes, both in soils and water, leading for instance to increasing nutrient uptake. Mineralization and nitrification are also temperature dependent processes, and may be speed in a warming climate. Climate also affects physico-chemical processes such as weathering of rocks and soils, changing the amount and typology of solute release from the catchment to the lakes. In this context, even more important than the direct role of temperature, is the indirect effect of the change in snow cover. A reduction of snow cover in space and time means indeed a greater exposure of rocks and soils in the watersheds, and possibly a greater amount of solutes export to surface water. In this study we focused on the possible effect of these processes on long-term changes in the chemistry of alpine lakes. We analysed long-term chemical data (major ions and nutrients) available for a number of high altitude lakes in different regions of the Alps and analysed changes in relation to the main meteorological variables (temperature precipitation, snow cover). Continuous data over a 30 year period are available for a few lakes in the Central-Western Alps. These data allow us to analyze both long- and short-term trends, considering for instance the interannual variability in lake chemistry in relation to striking meteorological condition. Beside this high-frequency monitoring of a few sites, surveys of lakes in different Alpine areas (e.g. Ossola and Sesia Valleys, Piedmont; Stelvio National Park, Lomabardy) allowed a comparison with data available on these sites since the 1980s from previous research projects. This dataset altogether was used to test the occurrence of common trends in the chemistry of high-altitude lakes over the last 30 years. A general tendency to increasing solute content during the observation period was detected, with more pronounced trends at lakes with highly mineralized water. A positive trend of sulphate concentrations was observed at most of the lakes, sharply in contrast with the decrease of sulphate deposition which has occurred in the Alpine region as over most of Europe in the last decades. Hence a climate signal may be hypothesized to explain this trend. The observed trends in the Alps were compared with those occurring at mountain lakes in other remote regions. Long-term chemical data are available in particular for two lakes in the Khumbu Valley (Himalaya, Nepal), as part of the LTER network. These lakes showed positive trends of the conductivity and major ions, more evident in the last few years. As for the Alps, also these trends may be put in relation to changing climate condition, in particular to increasing temperature and reduced snow cover in the catchment.