We present a method for the rapid determination of the moment tensor suitable for application to regional earthquakes up to 3000 km distance. The algorithm is based on the inversion of long-period waveforms in the time-domain and is routinely applied to significant events of the Mediterranean, from Iran to the Azores, using digital data recorded by the MEDNET regional network. We show results for 20 significant earthquakes of 1990--1992, including the large shocks in Romania (May 30, 1990), Iran (June 20, 1990), Caucasus (April 29, 1991), Turkey (March 13, 1992) and Egypt (October 12, 1992), the damaging Italian earthquakes of Potenza (May 5, 1990) and Siracusa (December 13, 1990), unusual events in the Southern Mediterranean (November 11, 1990) and Holland (April 13, 1992) and the recent shocks of October 23, 1992 in Morocco and Caucasus. The comparison with published focal mechanisms and Centroid Moment Tensors show our results to be consistent with those retrieved using global data and local networks, proving that an advanced regional seismic network is capable of providing accurate, rapid control of regional seismicity. ¿American Geophysical Union 1993