Natural killer cells (NK) are the first arm of the innate immune system in defense against tumor and infection. 16 distinct Killer-cell immunoglobulin-like receptors (KIRs) are involved in orchestrating NK cell function. The KIR family contains 14 genes and 2 pseudogenes. Six of these receptors are activating (aKIR) and the remaining receptors are inhibitory KIRs (iKIR), that interact with MHC-I molecules; producing signals which stop NK cell function. In the current study, we have investigated the genomic diversity of KIRs and determining the A and B haplotypes as well as Bx subsets in 119 patients with bladder cancer and 200 healthy controls to find out if there is an association between KIR system and susceptibility to bladder cancer. Polymerase chain reaction with sequence specific primers (SSP–PCR) typing system was used to determine the KIR gene profile. The results implicated decreased frequency of inhibitory KIR2DL2 and activating KIR2DS2 while increased frequency of CxT4 genotypes in patients compared with healthy controls. Among Bx subsets, the CxT4 gene cluster is more frequent in bladder cancer patients compared to controls. Our results provide a conclusion that KIR2S2 and KIR2L2 may play a protective role against bladder cancer development while the CxT4 gene cluster may underlie susceptibility to bladder cancer in Iranian population.