Estimates of $\varepsilon\varepsilon$'

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}.