  We study the effects of gluon interference in the production and
semi-leptonic decay of a t-tbar pair above threshold at the Next Linear
Collider (NLC). We calculate all matrix elements to next-to-leading order and
use the resulting expressions for the development of a Monte Carlo event
generator. Our results show effects at the level of 10% in differential
cross-sections. We thus extend previous results obtained by analytical means in
the soft-gluon limit.
