The interleukin 1 (IL-1) gene family includes three members (IL-1-alpha, IL-1-beta and IL-1Ra) that mediate immune and inflammatory responses through two specific cell surface receptors. Cytosine to thymine transitions at codons -889 and -511 in the IL-1-alpha and IL-1-beta genes, respectively, and an 86-base pair repeat in the IL-1Ra are believed to influence gene transcription. We have genotyped these three polymorphisms in 90 donor/recipient pairs undergoing unrelated donor bone marrow transplantation (BMT) at the University of Minnesota. We found no association between the occurrence of acute GVHD and donor and/or recipient polymorphisms of any of the three IL-1 genes. The presence of at least one IL-1alpha- 889 T allele in the donor was associated with significantly improved survival in univariate analysis (survival at 1 year 40% C/C donor, 68% T/C donor, 75% T/T donor, P < 0.01). Multiple regression analysis showed that if the donor and recipient each possessed the IL-1alpha T allele there was significantly improved survival [relative risk (RR) 0.2, P < 0.01] and decreased treatment-related mortality (TRM; RR 0.2, P = 0.01). The presence of the IL-1beta T allele in donor and recipient was also associated with improved survival (RR 0.2, P < 0.01) and decreased TRM (RR 0.1, P < 0.01). These data suggest that donor polymorphism in IL-1alpha and IL-1beta might influence survival after unrelated donor BMT, but does not alter risk of GVHD.