Abstract: The present invention relates generally to a method of diagnosing, predicting and/or monitoring the development or progress of an inflammatory response in a mammal. More particularly, the present invention relates to a method of diagnosing, predicting and/or monitoring the development or progress of an inflammatory response by analysing one or both of activin or follistatin expression levels either in a subject mammal or in a biological sample derived from said mammal. The present invention further provides a method for predicting, diagnosing and/or monitoring conditions associated with or characterised by the onset of inflammatory response. Also provided are diagnostic agents useful for detecting activin and/or follistatin expression levels.