Cleanness is a poem in alliterative verse in Middle English dating from the first half of the 14th century. It is attributed to the anonymous Pearl Poet.

The poem is attributed to the Pearl Poet because it is found solely in the Pearl manuscript, Cotton Nero A x. That manuscript contains Pearl, Cleanness, Patience, and Sir Gawayne and the Grene Knight. None of the poems has a title or divisions of chapters, but the breaks are marked by large initial letters of blue, and each poem has a single, full page illustration. Each of these poems is entirely unique to this one manuscript.

Cleanness is a description of the virtues of cleanliness of body and the delights of married love. It takes three subjects from the Bible as its illustrations: the Flood, the destruction of Sodom and Gomorrah, and the fall of Belshazzar. Each of these is described powerfully, and the poetry is among the finest in Middle English. In each case, the poet warns his readers about the dangers of defilement and, at the same time, the joys of purity.