Repetin is a 784 amino acid secreted protein that belongs to the S100-fused protein family. Repetin is an extracellular epidermal matrix protein that is expressed in the epidermis and at high levels in eccrine sweat glands, the inner sheaths of hair roots and the filiform papilli of the tongue. A multifunctional epidermal matrix protein, repetin is involved in the cornified cell envelope formation. Containing two EF-hand domains, repetin’s recombinant N-terminal domain binds calcium reversibly. Repetin and trichohyalin may compensate for absent loricrin. The repetin gene contains three exons, two introns and spans at least 5.6 kb. The repetin gene is conserved in cow, mouse and rat, and maps to human chromosome 1q21.3.