Between February 1972 and December 1987, 192 adults (greater than or equal to 18 years old) with acute lymphoblastic leukemia were transplanted using genotypically HLA-identical marrow donors. Median patient age was 23 years. Eighty-nine patients were in marrow remission and 103 were in relapse. Conditioning regimens included chemotherapy alone (three patients) or in combination with 9.2-17.5 Gy total body irradiation (189 patients). Graft-versus-host disease (GVHD) prophylaxis consisted of methotrexate and/or cyclosporine. Seventy-nine patients developed grades II-IV acute GVHD and 28 of 122 patients who survived at least 100 days developed chronic GVHD. Relapse-free survival at 5 years was 21% for patients transplanted in first remission, 15% for those in greater than or equal to 2nd remission, and 12% for those transplanted in relapse. Patient and donor characteristics were evaluated in multivariate analyses for their effect on development of acute GVHD, survival, relapse, and relapse-free survival. An increased risk of developing acute GVHD was associated with increasing donor age. Variables significantly associated with both increased survival and relapse-free survival included transplantation in first remission, younger patient age, and not developing interstitial pneumonia. A decreased probability of relapse was associated with transplantation in first remission, male patient sex, and grades II-IV acute GVHD.