Cytokines are associated with inflammatory responses including febrile non-hemolytic transfusion reactions (FNHTR). Moreover, there are some polymorphisms of these cytokine genes associated with different levels of gene expression. The aim of the present study was to investigate the association of inflammatory cytokine gene polymorphisms with the occurrence of FNHTR in multitransfused patients. We studied two groups of transfused patients: one presenting FNHTR before 20 transfusions of red blood cells concentrates and the other which never presented FNHTR even after 20 transfusions. The gene polymorphisms studied were IL1B - 511C/T and +3953C/T, IL1RN ( intron 2, variable number tandem repeat), IL6-174G/C, IL10 - 1082G/A and - 819C/T, TNF-308G/A and LTA+253G/A using polymerase chain reaction and restriction digestion or sequencing methods. An association of IL1RN*2.2 genotype with the occurrence of precocious FNHTR ( P < 0.025) was detected. This allele and this genotype have been related with higher serum levels of interleukin (IL)-1 beta in vivo and higher promoter activity. No other association was demonstrated. The association of gene polymorphisms related with the increase of inflammatory cytokine gene expression may be a relevant factor in FNHTR and requires confirmation.163184191