  We obtain expressions for the mass and angular momenta of rotating black
holes in anti-de Sitter backgrounds in four, five and higher dimensions. We
verify explicitly that our expressions satisfy the first law of thermodynamics,
thus allowing an unambiguous identification of the entropy of these black holes
with $\ft14$ of the area. We find that the associated thermodynamic potential
equals the background-subtracted Euclidean action multiplied by the
temperature. Our expressions differ from many given in the literature. We find
that in more than four dimensions, only our expressions satisfy the first law
of thermodynamics. Moreover, in all dimensions we show that our expression for
the mass coincides with that given by the conformal conserved charge introduced
by Ashtekar, Magnon and Das. We indicate the relevance of these results to the
AdS/CFT correspondence.
