In a tokamak, the leading candidate for a future fusion reactor, heat transport is generally much higher than expected from neo- classical theory (based on Coulomb collisions). This so-called anomalous transport hampers progress to a fusion reactor. Therefore regimes with reduced heat transport are strongly focused upon. In the past decade several such regimes have been found. They are characterised by regions of strongly reduced transport, so-called transport barriers. Such barriers may sit at the edge of the plasma, for example in the H-mode, or in the interior. The latter, called Internal Transport Barriers (ITBs) are subject of this presentation. ITB's need not be present in the ion and electron channel simultaneously. This may indicate that electron and ion ITBs are caused by different mechanisms. The presentation will focus on results obtained in the Dutch tokamak RTP and the joint European experiment JET.