A small, secretive, mouse-like species, the alpine shrew (Sorex alpinus) is slender-bodied and short-legged, with conspicuous whiskers and a characteristically long, pointed, highly manoeuvrable snout. Slightly larger than the common shrew (Sorex araneus), the alpine shrew has the longest tail of all European shrew species, measuring almost the same size as the length of the head and body combined.

The short, sleek fur of the alpine shrew is uniformly slate-grey or greyish-black on the upperparts, and is generally slightly lighter, or sometimes white, on the underparts. The whiskers are long and white, and the snout and feet are fleshy pink. A pale white ring is often visible around the small eyes. The tail is generally pinkish-brown, and is hairy in juveniles but hairless in the adult. Young and female alpine shrews may sometimes have a white tip to the tail. The teeth of the alpine shrew are coloured brown to purplish at the ends, which is caused by the high content of iron.