  We study the properties of quasi-distributions or Wigner measures in the
context of noncommutative quantum mechanics. In particular, we obtain necessary
and sufficient conditions for a phase-space function to be a noncommutative
Wigner measure, for a Gaussian to be a noncommutative Wigner measure, and
derive certain properties of the marginal distributions which are not shared by
ordinary Wigner measures. Moreover, we derive the Robertson-Schr\"odinger
uncertainty principle. Finally, we show explicitly how the set of
noncommutative Wigner measures relates to the sets of Liouville and
(commutative) Wigner measures.
