  We present a chronological review of the progress in calculating weak matrix
elements using staggered fermions. We review the perturbative calculation of
one-loop matching formula including both current-current diagrams and penguin
diagrams using improved staggered fermions. We also present preliminary results
of weak matrix elements relevant to CP violation calculated using the improved
(HYP (II)) staggered fermions. Since the complete set of matching coefficients
at the one-loop level became available recently, we have constructed lattice
operators with all the $g^2$ corrections included. The main results include
both $\Delta I = 3/2$ and $\Delta I = 1/2$ contributions.
