[en] Very recently, ROSAT and ASCA have been able to detect X-rays from protostars typically 10 times younger than T Tauri stars (i.e., having ages ∼ 10⁵ yrs), in spite of their heavy extinction (A_V ∼ 30 - 60). The intrinsic luminosities, either quiescent or in the form of flares, are ∼ 10 times higher than T Tauri stars or more. In one particular case (a well-documented protostar in the nearby ρ Oph cloud, YLW15), the (L_X(L_bol)) ratio has been > 1 during a 'superflare'. This high value implies not a stellar origin, but rather (for the first time) star-disk and/or star-envelope magnetic interactions, not unlike those invoked for compact objects. The present status of X-ray emission by protostars, as seen with ROSAT and ASCA, is summarized