The European Workshop on Inflatable Space Structures will be held on the 10th, 11th and 12th of May 2011 in Noordwijk, The Netherlands. It is the 5th European Workshop on balloons, inflatable habitat modules, flexible materials, rigidisation concepts, folding techniques. Inflatable Space Structures offer the possibility to deploy in-orbit large structures, which can be packaged for launch. In order to make this packaging efficient, the structure shall fulfill several requirements: structural member, but also thermal protection, protection against radiations, repair capability, integrity during inflation, permeability properties, etc. The European workshop on Inflatable Space Structures provides a platform for discussions and exchange between engineers in the area of inflatable space structures. The workshop, this year at its 5th edition, provides the opportunity to researchers and industries to present their recent work and to present their programmes and their needs. The workshop will consist in a series of presentations and poster sessions. Parallel to the workshop, an exhibition on Inflatable Space Structures related hardware will be organized. This exhibition will give the conference attendants the opportunity to see the latest products in the field of Inflatable Space Structures.