A sizeable difference in the differential production cross section
of top and antitop quarks, respectively, is predicted for
hadronically produced heavy quarks.
It is of order $\alpha_s$ and arises from the
interference between charge odd and even amplitudes respectively.
For the TEVATRON it amounts to approximately $5-10\%$
in the region where the cross section is large and could
therefore be measured in the next round of experiments.
At the LHC the asymmetry can be studied by selecting
appropriately chosen kinematical regions.
