  We study moduli spaces of meromorphic connections (with arbitrary order
poles) over Riemann surfaces together with the corresponding spaces of
monodromy data (involving Stokes matrices). Natural symplectic structures are
found and described both explicitly and from an infinite dimensional viewpoint
(generalising the Atiyah-Bott approach). This enables us to give an intrinsic
symplectic description of the isomonodromic deformation equations of Jimbo,
Miwa and Ueno, thereby putting the existing results for the six Painleve
equations and Schlesinger's equations into a uniform framework.
