Ten patients with acute leukemia (AL) in early relapse after allo-BMT were treated with a modified MEC (mitoxantrone, etoposide and Ara-C) regimen followed by donor PBPC collected after mobilization with G-CSF. Seven patients achieved CR or had normal hemopoietic reconstitution: two had an early relapse at days +53 and +48, two patients died from acute GVHD at days +31 and +96, one died of interstitial pneumonia at day +55, and two patients experienced long-term survival. One patient with refractory disease and nodal involvement who did not respond to the first BMT had overt expansion of the leukemia at day +36; one patient with Ph+ ALL and one with ANLL evolving from MDS, both with skin involvement, had blast cells in peripheral blood at day +27 and +26, respectively. Transient cytopenia occurred in all patients; a normal granulocyte and platelet count was achieved within 3 weeks in all patients but one; acute GVHD occurred in six patients, and four had chronic GVHD. This approach is feasible in patients in early relapse after allo-BMT. It assists prompt re-establishment of normal donor hematopoiesis avoiding the prolonged cytopenia observed after donor lymphocyte infusion in AL patients relapsed after allo-BMT.