There is an increasing interest in exploiting the immunomodulatory effects of helminths and their products in treatment of diseases such as allergy, autoimmunity and inflammatory bowel disease. Detailed examination of the ways in which helminth derived products interact with the host immune system and with host physiology has revealed that these may be multifaceted and have almost certainly arisen following co-evolution of helminths and their hosts. Clinical trials have been initiated with encouraging results in the treatment of inflammatory bowel disease and also Multiple Sclerosis. Identification of key pathways that are manipulated by helminths to ameliorate ongoing inflammatory conditions increases the prospect of developing novel therapies for the treatment and possible prevention of a range of debilitating and life threatening conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.