  We investigate the large-scale clustering of radio sources in the Green Bank
and Parkes-MIT-NRAO 4.85 GHz surveys by measuring the angular two-point
correlation function w(\theta). Excluding contaminated areas, the two surveys
together cover 70 per cent of the whole sky. We find both surveys to be
reasonably complete above 50 mJy. On the basis of previous studies, the radio
sources are galaxies and radio-loud quasars lying at redshifts up to z \sim 4,
with a median redshift z \sim 1. This provides the opportunity to probe
large-scale structures in a volume far larger than that within the reach of
present optical and infrared surveys. We detect a clustering signal w(\theta)
\approx 0.01 for \theta = 1\degr. By assuming an evolving power-law spatial
correlation function in comoving coordinates \xi(r_c,z) = ( r_c / r_0
)^{-\gamma} (1+z)^{\gamma-(3+\epsilon)}, where \gamma = 1.8, and the redshift
distribution N(z) of the radio galaxies, we constrain the r_0--\epsilon
parameter space. For `stable clustering' (\epsilon = 0), we find the
correlation length r_0 \approx 18 Mpc/h, larger than the value for nearby
normal galaxies and comparable to the cluster-cluster correlation length.
