Cortinarius semisanguineus is a medium-sized mushroom with a pale brown to ochre cap, and bright blood-red gills.

[1] The cap is campanulate (bell-shaped), and later flattens, but retains a broad umbo (shield-like central boss).

They are initially blood-red, but turn cinnamon-brown on aging, giving a spore print of the same colour.

[2] A similar species, Cortinarius phoeniceus has a redder cap, and more distinct red cortinal remnants around the stem.

It is often abundant under young spruce in plantations on acid soil,[3] appearing from August to November.