In recent years, several functional polymorphisms, particularly, SNPs have been identified in cytokines and their receptor genes that regulate levels of cytokine expression. These have been implicated as immune prognostic markers in diseases, including differential response to therapy and as biomarkers of graft outcome following organ and stem cell transplantation. Population distribution of cytokine gene polymorphisms (CGPs) reveals significant variations in allele frequencies in different ethnic groups and this might explain, to some extent, the observed differences in SNP associations with various diseases and immune-pathologies. A number of molecular methods are available for defining CGPs. These include PCR-SSP, AFLP, Taqman probe assays as well as sequencing based typing. Of these, the PCR-based sequence-specific primer based test is the most widely accepted technique. This chapter describes steps involved in this procedure along with sources for procuring essential reagents. An important aspect of CGP analyses is the correct interpretation of results particularly determination of their multilocus haplotypes.