  We review the latest calculations of the next-to-leading $\DSone$ effective
Hamiltonian, relevant for $K\to \pi\pi$ transitions. Numerical results for the
Wilson coefficients are given for different regularization schemes. Predictions
of $\epse$, obtained using different approaches to evaluate the relevant
hadronic matrix elements, are compared. Given the present value of the top
mass, $m_t=(174\pm 17)$ GeV, all the analyses, in spite of the large
theoretical uncertainties, indicate that the value of $\epse$ is smaller than
$1\times 10^{-3}$.
