Lepidium seydelii (Brassicaceae), a new species from Namibia, is described and illustrated. It is easily distinguished from the closely related to L. divaricatum and all other southern African species of Lepidium by having pubescent, elliptic to elliptic-ovate fruit 1.3–1.6 × 1–1.2 mm and fruiting pedicels densely hirsutulous all around. A key distinguishing the four species of Lepidium native to Namibia is presented.