The present invention relates generally to a method of reducing unwanted airway tissue mucus secretion in a mammal and to agents useful for same. More particularly, the present invention relates to a method of reducing airway tissue mucus hypersecretion in a mammal by downregulating the functional level of activin or upregulating the functional level of follistatin. The method of the present invention is useful, inter alia, in the treatment and/or prophylaxis of conditions characterised by airway tissue mucus dysfunction, such as overproduction of mucus or decreased mucus clearance, and where a reduction in mucus secretion levels would thereby alleviate the condition.
