Human cathelicidin antimicrobial peptide LL-37 (LL-37) is an antimicrobial peptide derived from its precursor protein hCAP18, which is an only cathelicidin in human. LL-37 not only serves as a mediator of innate immune defense against invading microorganisms, but it also plays an essential role in tissue homeostasis, regenerative processes, regulation of proinflammatory responses, and inhibition of cancer progression. Therefore, LL-37 has been considered as a drug lead for diseases. However, high levels of LL-37 may reduce cell viability and promote apoptosis of osteoblasts, vascular smooth muscle cells, periodontal ligament cells, neutrophils, airway epithelial cells and T cells. Recent evidence reveals that LL-37-derived short peptides possess similar biological activities as the whole LL-37 with reduced cytotoxicity. Thus, such small molecules constitute a pool of potential therapeutic agents for diseases.