  We have analyzed a set of deep ROSAT observations with a total sky coverage
of 40 square degrees to search for clustering of faint X-ray sources. Using the
resulting catalog of discrete X-ray sources, we detect, for the first time in
X-rays, a positive correlation on angular scales of 0.5'-10'. When corrected
for a bias due to limited spatial resolution which amplifies the correlation,
the observed angular correlation function agrees well with that expected from
the spatial correlation of optically selected quasars, provided that they
comprise an appreciable fraction (>= ~50%) of detected X-ray sources.
