  We construct an invariant of 3-manifolds using a modification of the
Kontsevich integral and Kirby's calculus. This invariant, as expected in
perturbative Chern-Simon theory, takes values in the algebra of oriented
3-valent graphs. This algebra is a Hopf algebra, graded by half the number of
vertices in 3-valent graphs. The degree 1 term of the invariant coincides with
Casson-Walker-Lescop invariant. The degree $n$ term is constructed out of the
universal Vassiliev invariant of links of degree less than or equal to $(l+1)n$
where $l$ is the number of link components.
