The pisiform bone (also called pisiforme or lentiform bone) is a small knobbly, pea-shaped wrist bone. It forms the ulnar border of the carpal tunnel.

The pisiform bone is found in the proximal row of the carpus. It is located where the ulna (inner bone of the forearm when in anatomical position) joins the carpus (wrist). It articulates only with the triquetral.

It is a sesamoid bone.

The pisiform bone may be known by its small size, and by its presenting a single articular facet. It is situated on a plane anterior to the other carpal bones and is spheroidal in form.

The etymology derives from the Latin pīsum which means "pea".