Brown adipose tissue (BAT) plays an important role in nonshiverthing thermogenesis, thermoregulation and body mass regulation in small mammals. However, in human, the presence of brown adipose tissue was thought to be relevant only in infants, with negligible physiologic relevance in adult. Recently, using 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomographic and computed tomographic (PET-CT) scans showed that adults retain metabolically active BAT depots that can be induced in response to cold and sympathetic nervous system activation. These findings highlight BAT as a potential relevant target for pharmacological and gene expression manipulation to combat human obesity. We reviewed the recent research progresses of BAT in human and its potential functional significance.