  We define and investigate pairings of multiplier Hopf algebras. It is shown
that two dually paired regular multiplier Hopf ($*$-)algebras $A$ and $B$ yield
a quantum double multiplier Hopf ($*$-)algebra which is again regular.
Integrals on $A$ and $B$ induce an integral on the quantum double. The results
generalize pairing and quantum double construction from ordinary Hopf algebras
to multiplier Hopf algebras.
