HST observations of three radio galaxies at redshift z~=1

The first results of a programme to image a sample of radio galaxies at redshift z~=1 with the Hubble Space Telescope are reported in this Letter. The images of the three galaxies presented here (3C368, 3C324 and 3C265) show a wealth of fine structure down to the resolution limit of the HST. All three systems show a clear alignment of the optical emission with the axis of the double radio source, a phenomenon first noted by Chambers et al. and McCarthy et al. The appearance of the alignment is, however, quite different in each case. It is argued that the remarkable structures seen in the HST images are different manifestations of activity associated with the radio source phenomenon, with the alignment effects being a result of at least two different mechanisms.