  We employ the framework of Bethe-Salpeter equation under Covariant
Instantaneous Ansatz (CIA) to study the leptonic decays of vector mesons. The
structure of hadron-quark vertex function Gamma is generalized to include
various Dirac covariants (other than i gamma dot epsilon) from their complete
set. They are incorporated in accordance with a naive power counting rule order
by order in powers of the inverse of the meson mass. The decay constants for
rho omega and phi mesons are calculated with the incorporation of leading order
covariants.
