A&a Manuscript No. High Resolution Radio Imaging of the Extremely Distant Quasars 1251{407, 1351{018, 1354{174 and 1508+572

We present results of rst epoch high resolution imaging observations of four extremely distant quasars. The sample includes the only two radio-loud quasars at redshift z > 4 known to the date of observa-The milliarcsecond scale structures of these quasars are dominated by compact cores. The two z > 4 quasars are unresolved on the baselines observed. We show that the apparently less prominent mil-liarcsecond scale extended radio structures in high redshift quasars than in their low redshift counterparts may be explained by the diierence in spectral indices of the cores and jets.