  We test the hypothesis that the polarization vectors of flat-spectrum radio
sources (FSRS) in the JVAS/CLASS 8.4-GHz surveys are randomly oriented on the
sky. The sample with robust polarization measurements is made of $4155$ objects
and redshift information is known for $1531$ of them. We performed two
statistical analyses: one in two dimensions and the other in three dimensions
when distance is available. We find significant large-scale alignments of
polarization vectors for samples containing only quasars (QSO) among the
varieties of FSRS's. While these correlations prove difficult to explain either
by a physical effect or by biases in the dataset, the fact that the QSO's which
have significantly aligned polarization vectors are found in regions of the sky
where optical polarization alignments were previously found is striking.
