We compared the effects of cyclosporin A (CsA) alone as graft-versus-host disease (GVHD) prophylaxis vs cyclosporine with short-course methotrexate (MTX) in patients with thalassemia. In all, 140 patients were enrolled in this study. The first group, of 50 patients, received CsA alone at 3 mg/kg i.v. from day -2 to +5 followed by 12.5 mg/kg p.o., which was tapered according to the patient's condition. The other group, of 90 patients, received the combination of CsA+MTX in which CsA was used with the above-mentioned dose and MTX was on 10 mg/m(2) day +1 and 6 mg/m(2) on days +3 and +6. Incidence of acute GVHD grade II-IV in the CsA group was 78% and in the CsA+MTX group was 52.2%, which was statistically significant (P=<0.001). There were no significant differences in the incidence of chronic GVHD between the two groups. The mean neutrophil engraftment to 0.5 x 10(9)/l was 14 and 23 days for CsA group and CsA+MTX group, respectively (P=<0.001). There were no significant differences for platelet recovery between the two groups. Graft failure in the CsA and CsA+MTX groups was seven (14%) and nine (10%) patients, respectively (P=0.58). Overall survival in the CsA and CsA+MTX groups was 77 and 85%, respectively. Disease-free survival in the CsA and CsA+MTX groups were 58 and 80%, respectively.