The pine marten adult is the size of a small domestic cat; it is slender with dense, chocolate-brown fur and a long bushy tail. It has a cream-coloured bib on the throat. The male measures on average 68 cm from nose to tip of tail. The female is slightly smaller. It is a member of the weasel family. In continental Europe another species, the beech or stone marten (Martes foina) is also found. In North America there are two species of the marten, the fisher (Martes pennanti) and the American marten (Martes american) which are very similar to the pine marten.

They move quickly along the ground, rarely emerging into open spaces. They are expert at climbing trees. They are mostly likely to be seen in the evening or at night, although they do come out during the daytime in summer months. They have an alert and timid presence.