A short summary of results for top-quark pair production in
association with a jet with NLO QCD off-shell effects at the LHC is
given. The calculation is based on the matrix element for the $pp\to
e^+ \nu_e \mu^-\bar{\nu}_\mu b\bar{b} j$ process. All quantum effects
are properly accounted for, which amounts to including all Feynman
diagrams that result in this final state with interference effects as
well as non-zero top-quark width effects. Results for total cross
sections and a few differential distributions at the LHC Run1 energy
of $\sqrt{s}=8$ TeV are presented. In addition, the size of top-quark
off-shell effects is quantified for the total cross section in
presence of rather inclusive cuts on all final states. Numerical
results shown in this proceedings have been obtained with the
\textsc{Helac-NLO} Monte Carlo program.