Many glaciers on the globe have significantly receded during the last decades in response to climate change. Most studies in this context have focused on biotic assemblages in glacial-fed (kryal) streams, suggesting a high potential loss in macroinvertebrate diversity in kryal streams as glacier-flow contributions diminish. Alpine basins also comprise a large number of non-glaciated (krenal, rhithral) streams likely inhabited by macroinvertebrate assemblages different than those common to kryal streams. We examined macroinvertebrate assemblages in 41 non-glacial tributaries within 5 different glacial catchments in the Swiss Alps. The data were used to determine their contribution and role in the overall biodiversity of glacial catchments. We found an astonishing high diversity of macroinvertebrates in these tributaries with 64 taxa in 12 orders being identified overall and up to 24 different taxa found at individual sites. The abundance, taxonomic richness (α-diversity) and assemblage composition (β-diversity) differed highly between tributaries, suggesting their role as habitat for non-glacial specialists and as potential refugia for alpine species in general. The tributaries showed high individuality in physico-chemical factors as well as in taxonomic composition. Most of the taxa found could be defined as rare when comparing abundances, highlighting the importance of an analytical approach including all taxa. These results indicate that non-glacial tributaries contribute significantly to the biodiversity of alpine running waters and may play an important role in sustaining alpine biodiversity under landscape transformation resulting from climate change.