  We investigate the associations between background galaxies and foreground
clusters of galaxies due to the effect of gravitational lensing by clusters of
galaxies. Similar to the well-known quasar-galaxy ones, these associations
depend sensitively on the shape of galaxy number-magnitude or number-flux
relation, and both positive and ``negative" associations are found to be
possible, depending on the limiting magnitude and/or the flux threshold in the
surveys. We calculate the enhancement factors assuming a singular isothermal
sphere model for clusters of galaxies and a pointlike model for background
sources selected in three different wavelengths, $B$, $K$ and radio. Our
results show that $K-$ selected galaxies might constitute the best sample to
test the ``negative" associations while it is unlikely that one can actually
observe any association for blue galaxies. We also point out that bright radio
sources ($S>1$ Jy) can provide strong positive associations, which may have
been already detected in 3CR sample.
