CERN-LHC. The production of prompt D$_s^+$ mesons was measured for the first time in collisions of heavy nuclei with the ALICE detector at the LHC. The analysis was performed on a data sample of Pb-Pb collisions at a centre-of-mass energy per nucleon pair, $\sqrt{s_{\rm NN}}$, of 2.76 TeV in two different centrality classes, namely 0-10% and 20-50%. The nuclear modification factor $R_{\rm AA}$ was computed by comparing the $p_{\rm T}$-differential production yields in Pb-Pb collisions to those in proton-proton (pp) collisions at the same energy. The production ratios D$_s^+$/D$^0$ and D$_s^+$\D$^+$ were also measured in Pb-Pb collisions and compared to their values in proton-proton collisions. ; Other ; Ratio of D$_s^+$ to D$^0$ meson yield in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$=2.76 TeV in the centrality class 0-10% in |y| $ϕπ^+$->$K^+K^-π^+$ : 0.0224. Branching ratio of D$^0$->K$^-π^+$ : 0.0388.