  We consider the recent measurement of the top quark forward-backward
asymmetry at the Fermilab Tevatron, which shows a discrepancy of slightly more
than 2$\sigma$ compared to the SM prediction. We find that $t$-channel exchange
of a color sextet or triplet scalar particle can explain the measurement, while
leaving the cross section for $t \bar{t}$ production within measured
uncertainties. Such particles have good discovery prospects by study of the
kinematic structure of $t \bar{t}$+jets at the LHC.
