ROSAT HRI observations of radio-loud AGN

We present the results of three ROSAT HRI observations of AGN expected to r eside in clusters of galaxies. Although the exposures were truncated by the premature end of the ROSAT mission, valuable information could be achieved which greatly improved upon the previous PSPC results. For RGB 1745+398 we could separate the cluster emission from that of the BL Lac and could confirm the cluster parameters obtained from optical follow- up observations. In MRC 0625-536 the flux from the central point source con tributes less than 3% to the total X-ray flux and the eastern component of the dumbbell galaxy seems to be the X-ray emitter. RXJ1234.6+2350 appears t o be extended in X-rays. The X-ray flux is centered on a quasar, but optica l spectroscopy indicates that the nearby radio galaxies reside in a previou sly unknown cluster at redshift z similar to 0.134.