Chamomile (Matricaria recutita L., Chamomilla recutita L., Matricaria chamomilla) is one of the most popular single ingredient herbal teas, or tisanes. Chamomile tea, brewed from dried flower heads, has been used traditionally for medicinal purposes. Evidence-based information regarding the bioactivity of this herb is presented. The main constituents of the flowers include several phenolic compounds, primarily the flavonoids apigenin, quercetin, patuletin, luteolin and their glucosides. The principal components of the essential oil extracted from the flowers are the terpenoids alpha-bisabolol and its oxides and azulenes, including chamazulene. Chamomile has moderate antioxidant and antimicrobial activities, and significant antiplatelet activity in vitro. Animal model studies indicate potent antiinflammatory action, some antimutagenic and cholesterol-lowering activities, as well as antispasmotic and anxiolytic effects. However, human studies are limited, and clinical trials examining the purported sedative properties of chamomile tea are absent. Adverse reactions to chamomile, consumed as a tisane or applied topically, have been reported among those with allergies to other plants in the daisy family, i.e. Asteraceae or Compositae.