The ubiquitous presence of transparent exopolymer particles (TEP) in various water sources of membrane-based treatment plants and their ability to adhere to surfaces (high stickiness) and to initiate biofilm formation have led some experts to suggest that TEP may have a major role in organic and biological fouling of membrane systems. This paper aims discuss the latest knowledge on the possible link of TEP to membrane fouling, assess the currently available techniques to identify/measure TEP and how this can be applied in membrane fouling studies. Staining with Alcian blue is so far the most...