Activins are transforming growth factor beta superfamily members, which were originally identified as inducers of follicle-stimulating hormone release from the pituitary. In recent years, however, additional functions of activins have been discovered, including a role in the morphogenesis of various tissues and organs. In addition, they have been identified as novel players in inflammation and repair, and are most likely involved in the pathogenesis of inflammatory and fibrotic human diseases. In this review we highlight recent data regarding the expression and function of activins in tissue repair, fibrosis, and inflammation.