Four species of Cleome with small flowers, 6 stamens, petals without appendages, spreading to erect capsules, and hairy seeds, are recognized in the Horn of Africa region: C socotrana in the Socotra archipelago (Yemen), C. hadramautica, sp. nov., in southern Yemen, C. omanensis, comb. nov., in the Mahrah Region of Yemen and in Oman, and C. alhescens in northern Somalia. C. socotrana is lectotypified and a key to the species treated is provided.