Chinese black tea extract (CBTE) fermented with Aspergillus sp. significantly promoted hair growth after 2 weeks of topical application in shaved 6 week-old male C3H/He mice. The hair growth-promoting effect of CBTE was potentiated synergistically by capsaicin, which has no effect on hair growth by itself. CBTE displayed an affinity for estrogen receptor (ER)α, with an IC50 value of 74.8 µg/mL. This effect of CBTE might be mediated by the ERs, since a similar effect induced by orally administered soy isoflavone, a mixture of ERs ligands, has been reported to be synergistically potentiated by capsaicin.