Tokuyama has given a formula that is a deformation of the Weyl denominator formula for
sl(n). This formula can also be considered as a generalization of the ratio of
alternants formula for Schur functions. Here we derive a symplectic version of
Tokuyama's result, namely a deformation of Weyl's denominator formula for sp(2n).
We further show how it specializes to give symplectic versions of a number of classical identities.