In this paper we consider the following biharmonic equation with critical exponent
$\[$(P_{\varepsilon})\dvt\Delta^{2}u=Ku^{\frac{n+4}{n-4}-\varepsilon}$$
, u>0 in Ω and u=Δu=0 on
$\[$\curpartial \varOmega $$
, where Ω is a smooth bounded domain in
$\[$\mathbb{R}^{n}$$
, n≥5, ε is a small positive parameter, and K is a smooth positive function in
$\[$\overline{ \varOmega }$$
. We construct solutions of (Pε) which blow up and concentrate at strict local maximum of K either at the boundary or in the interior of Ω. We also construct solutions of (Pε) concentrating at an interior strict local minimum point of K. Finally, we prove a nonexistence result for the corresponding supercritical problem which is in sharp contrast to what happened for (Pε).