Recently others and we have shown that NK cells exhibit memory-like recall responses against CMV and HIV/SIV infections. Although the mechanism(s) have not been fully delineated, several groups have shown that the activating receptor NKG2C is elevated on NK cells in the context of rhesus CMV (rhCMV) or human CMV (hCMV) infections. CD94, which heterodimerizes with NKG2C is also linked to adaptive NK cell responses. Because non-human primates (NHP) play a crucial role in modeling HIV (SIV) infections, it is crucial to be able to assess and characterize the NKG2 family in NHP. Unfortunately it is not possible to detect CD94 using commercially available antibodies in NHP. Our work, a first for NHP, has focused on developing RNA-flow cytometry using mRNA transcripts as proxies distinguishing NKG2C from NKG2A. We have expanded the application of this technology and here we show the first characterization of CD94 (KLRD1)+ NK cells in NHP using multiparametric RNA-Flow cytometry. Peripheral blood mononuclear cells (PBMCs) from nave and matched acutely (n=4) or chronically (n=12) SIV-infected rhesus macaques were analyzed by flow cytometry using commercially available antibodies, determining expression of transcripts for NKG2A, NKG2C and CD94 (KLRC1, KLRC2 and KLRD1 respectively) on NK cells using RNA-flow cytometry. Our data show that KLRC1KLRC2+KLRD1+ NK cells decrease following chronic, but not acute, infection with SIV. This approach will allow us to investigate the kinetics of infection and NK memory formation, and will further improve our understanding of basic NK cell biology, especially in the context of SIV infection.Importance:Non-human primates play a crucial role in approximating human biology and many diseases that are difficult, if not impossible, to achieve in other animal models, notably HIV. Current advances in adaptive NK cell research positions us to address fundamental deficiencies in our fight against infection and disease at the earliest moments following infection, or substantially earlier in disease progression. Here we show that we can identify specific NK cell subpopulations that are modulated following chronic, but not acute, SIV infection. The ability to identify these subsets more precisely will inform therapeutic and vaccine strategies targeting an optimized NK cell response.