When thinking about circadian rhythms, the first thing that may come to mind is one’s sleep-wake schedule and its respective signaling pathways. While this is a common example of how the body relies on cues such as light or temperature to optimize function, this is not the only way these cues manifest on the cellular level. Circadian rhythms are a mechanism the immune system utilizes during injury or inflammation to eliminate dangers and regenerate damaged cells. These immune cells each have their own molecular clock, controlled by core clock genes. Understanding these exact mechanisms in relation to circadian rhythms can lead to improved treatments and remedies for cases or conditions that yield high inflammation or injury. Previous studies in our lab have shown that Influenza A Virus (IAV) survival and clearance in the lungs are subject to a time-of-day difference depending on the time of infection. An additional finding was that when natural killer (NK) cells were depleted with NK1.1 antibody, the time-of-day difference vanished. Since the data suggest that NK cells play a significant role in circadian response to IAV, we focused on the role of NK cells’ molecular clocks in IAV infection. This poster explains the impacts of knocking out the main clock gene in all NK cells compared to a group of mice with the clock gene intact when analyzing percentages of proliferating alveolar type 2 cells, macrophages, monocytes, and lymphocytes.