Discharges with internal transport barriers, ITBs, having a high fraction of bootstrap current is a promising route towards quasi-steady state operation of tokamaks. The underlying hypothesis for forming and sustaining ITBs is that the turbulence governing the transport under normal plasma conditions is suppressed by reversed magnetic shear and/or E ¥ B-shear [1]. It has been found that the shape of the q-profile is important for achieving ITBs, but the role of the locations of rational (integer) q-values and the minimum q still remain unclear. Sawtooth-like modes have been seen in ITB experiments [2-4]. In recent JET ITB-experiments produced by LHCD-preheat, large (m = 2, n = 1) and (3, 1) sawtooth-like modes appear in the reversed shear region of the barrier during the high performance phase when 1<qmin<2 and 2<qmin<3, respectively. These modes depend on the heating method. Minority heating of hydrogen produces in general a low sawtooth frequency with high amplitude in DTe, whereas minority heating of 3He and direct electron heating with ICRH produce higher frequency with lower amplitude. Continuous modes produced by the sawteeth are seen to locally flatten the angular velocity and thereby increase the second derivative of flow shear, which may reduce the turbulence. Depending on the size of the island the confinement could then either improve or deteriorate. The localisation of the MHD-modes around rational q-surfaces can be used for reconstructing the q-profiles. The change of the current distribution in the centre can be qualitatively determined from the motion of the inversion radius during sawtoothing. For mild sawteeth an expansion of the inversion radius is often seen, which implies that a reduction of the central current occurs in spite of sawtoothing and current diffusion. Continuous modes triggered by stronger sawteeth usually contract the inversion radius and thus enhance the current penetration through the barrier.