Ammonium trichlorotellurate (AS-101) is a synthetic non-toxic tellurium derivative, structurally similar to cisplatin, with immunostimulatory and anti-hair loss properties. Ammonium trichlorotellurate induces production of colony stimulating factor (CSF), interleukin-2 (IL-2), and IL-2 receptors by increasing the calcium ion influx through the cell membrane and subsequently exerts its immunostimulatory effects through the CSF-mediated increase in macrophage/granulocytes. This agent is also a potent inducer of interferon and a spectrum of cytokines such as IL-1, IL-6, and tumor necrosis factor (TNF). In animal studies, ammonium trichlorotellurate exerts its anti-hair loss effect by inducing anagen and obstructing spontaneous catagen via promoting follicular keratinocyte proliferation and interfering with terminal differentiation, respectively. AS-101 suppresses production of HIV-1. It inhibited reverse transcriptase activity and replication of human immunodeficiency virus type 1. RDDP and DDDP activities were impaired by the drug with calculated IC50 value of about 4 uM. Intravenous AS-101 was in trials in patients with HIV infections. AS-101, a small-molecule integrin αvβ3 and VLA-4 inhibitor is being developed by BioMAS in Israel for the treatment of genital warts, age-related macular degeneration and fertility preservation. Phase II clinical trials are ongoing. The drug was also undergoing phase II development in acute myeloid leukaemia, atopic dermatitis, chemotherapy-induced damage, myelodysplastic syndromes, thrombocytopenia, alopecia, psoriasis. However, development for these indications was discontinued.