Let X be a complex analytic space and 3 a coherent analytic sheaf over X. Jf Xis ^-complete, then H r (X, £F), the r-th cohomology of X with coefficients in 3, vanishes for r > q (cf. Andreotti-Grauert [1]). If moreover X is a g-complete manifold of dimension n and EF is locally free, then one has Ho~r(X, o) x ®EF)=Q by Serre's duality, where co x denotes the canonical sheaf of X and Hl~r denotes the cohomology with compact supports.In [2], A. Andreotti and E. Vesentini established an L 2 4heory on noncompact complex manifolds and showed that the vanishing of Hl~r(X, o) x ®3) is a direct consequence of certain a priori estimate as well as the vanishing of H r (X, 3}. Their approach is of interest since the cohomology vanishing is reduced to the solvability of a ^-equation with uniform estimates related to weighted L 2 -norms of Carleman type.The purpose of the present article is to give a relative version of their theory in the following situation.Let /: X-*S be a morphism between complex analytic spaces and £? a coherent analytic sheaf over X. The q-th direct image sheaf R q f*3! is a sheaf over S defined by (R%£F) x : = lim H q (f-\U) y 3*), where U runs through the u neighbourhoods of x. The #-th proper diiect image sheaf R^EF is defined by (R q f&) x :=limH q g(f-l (U\ 3"), where S denotes the family of supports consisting of the subsets of X on which/is proper.A recent result of K. Takegoshi shows that R q f*a) x =Q for q>Q in the above situation, if X is a complex manifold which is bimeromorphically equivalent to a Stein space.