In this paper we derive an interior estimate for the Galerkin method w
ith wavelet-type basis, Such an estimate follows from interior Galerki
n equations which are common to a class of methods used in the solutio
n of elliptic boundary value problems. We show that the error in an in
terior domain Omega(0) can be estimated with the best order of accurac
y possible, provided the solution ii is sufficiently regular in a slig
htly larger domain, and that an estimate of the same order exists for
the error in a weaker norm (measuring the effects from outside the dom
ain Omega(0)). Examples of the application of such an estimate are giv
en for different problems.