  We calculate the angular two-point correlation function of ultra-high energy
cosmic rays (UHECR) observed by AGASA and Yakutsk experiments. In both data
sets, there is a strong signal at highest energies, which is concentrated in
the first bin of the size of the angular resolution of the experiment. For the
uniform distribution of sources, the probability of a chance clustering is 4 x
10^{-6}. Correlations are absent or not significant at larger angles. This
favors the models with compact sources of UHECR.
