We present the results of the study of the relativistic jet of the quasar NRAO150. Our study confirm that the jet is seen at an extremely small angle to the line of sight and there is not a clear region to be identify as the core of the jet. The innermost regions of the jet show a counter-clockwise jet position angle swing at a high angular rate. We have studied the kinematic of the emission features into the innermost regions by fitting a model which explain the jet position angle swing as a rotation of the jet material following the toroidal magnetic field. This could be the first direct evidences about the helical structure of the magnetic field into the innermost regions of relativistic jets.