The familiar picture of magnetic collimation of jets is critiqued. Solutions are derived that explicity demonstrate the asymptotically parabolic nature of almost all stream lines, more or less consistent with previous discussions. It is then shown that collimation is too slow to be physically relevant when the flow in its uncollimated state is only weakly magnetized. In the alternative and more popular case, where the magnetic field is dynamically significant at all points on the flow, the divergence of field lines to large cylindrical radius implies kink instability