Posttransplantation non-Hodgkin lymphoma is a life-threatening complication after transplantation. Although pharmacologically suppressed adaptive immunity plays a major role in its development, the role of innate immunity in posttransplantation lymphoma is unknown. We assessed the 158 V/F polymorphism in the Fc-gamma receptor 3A gene (FCGR3A), killer cell immunoglobulin-like receptor (KIR) genotype, KIR ligand status, and a single nucleotide polymorphism affecting the production of interferon-gamma (IFN-gamma; +874 A/T) in 236 patients with posttransplantation lymphoma reported to the Collaborative Transplant Study. In addition, polymorphisms in the interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta) genes previously associated with lymphoma development were also typed. Using a split-cohort approach, gene/allele frequency was related to the 5-year patient survival after the diagnosis of lymphoma and compared with 100 control solid organ transplant recipients. FCGR3A and KIR genotype significantly influenced survival after diagnosis of posttransplantation lymphoma: the hazard of dying was reduced in homozygous carriers of the high-affinity V allele (hazard ratio 0.49, 95% confidence interval 0.29-0.82, P = .006), whereas carrying a genotype including KIR2DL2/KIR2DS2 increased the risk of dying (hazard ratio 1.49, 95% confidence interval 1.07-2.05, P = .02). KIR ligands and cytokine polymorphisms had no effect on survival. None of the genetic loci analyzed emerged as risk factors for lymphoma development.