Activins are secreted proteins members of the transforming growth factor-β family. They are involved in many biological responses including regulation of apoptosis, proliferation and differentiation of different cell types. Activins A, B and AB are highly expressed in adipose tissue, and in this review we will illustrate that activins have a role in several steps of physiological and pathological development of adipose tissue. Activin A has been shown to be a critical regulator of human adipocyte progenitor proliferation and a potent inhibitor of their differentiation. Activin A could also be a mediator of fibrosis observed in obese adipose tissue. Activin B/AB is proposed as a new adipokine having a role in energy balance and insulin insensitivity associated with obesity. Therefore, activin pathway could represent a potential therapeutic target both for controlling the size and the phenotype of the adipose precursor pool and for obesity-associated metabolic complications.International Journal of Obesity advance online publication, 28 February 2012; doi:10.1038/ijo.2012.28.