  Hadrons containing heavy-flavours, i.e. charm and beauty quarks, are unique
probes of the properties of the hot and dense QCD medium produced in heavy-ion
collisions. Due to their large masses, heavy quarks are produced at the initial
stage of the collision, almost exclusively via hard partonic scattering
processes. Therefore, they are expected to experience the full collision
history propagating through and interacting with the QCD medium. The parton
energy loss, which is sensitive to the transport coefficients of the produced
medium, can be studied experimentally by measuring the nuclear modication
factor ($R_{\rm AA}$) which accounts for the modication of the heavy-flavoured
hadron yield in Pb-Pb collisions with respect to pp collisions. In semi-central
Pb-Pb collisions, the degree of thermalization of charm quarks in the QCD
medium can be accessed via the measurement of the heavy flavour elliptic flow
$v_2$ at low $p_{\rm T}$ . At high $p_{\rm T}$, $v_2$ is sensitive to the
path-length dependence of heavy quark in-medium energy loss. The ALICE
collaboration has measured the production of open heavy flavour hadrons via
their hadronic and semi-leptonic decays at mid-rapidity and in the semi-muonic
decay channel at forward rapidity in pp, p-Pb and Pb-Pb collisions at 7, 5.02
and 2.76 TeV respectively. In this talk the current results on open
heavy-flavour $R_{\rm AA}$ and $v_2$ will be presented.
