Node-like receptor pyrin 3 is a tripartite protein composed of an amino-terminal pyrin domin (PYD), nucleotide binding NACHT domine, and a carboxy-terminal leucine-rich repeat (LRR) domine, and consider an intracellular sensor that detects a broad range signal and resulting in the formation and activation the NLRP3 inflammasome. This complex lead to the release of the inflammatory cytokines IL-1β, IL-18 which is important for host defense against invading pathogen. Modern evidence indicates that the NLRP3 inflammasome is involved in gestational hypertension. This study was conducted on fifty pregnant women and divided into two groups: 25 placentas from normotensive mothers having no hypertension before as the control group and 25 from gestational hypertension women as gestational hypertension group, obtained from the Department of Obstetrics and Gynecology in Almosil El Aam Hospital and Alkhanssa Teaching Hospital, Mosul city, Iraq. The placental tissue samples were collected from the central region and processed for an immunohistochemical technique to t h e expression of NLRP3 in placental tissue. The immunohistochemical study of t h e placenta of the gestational hypertension group showed the localization of NLRP3 protein and staining intensity in trophoblast, stroma, and endothelium villi were high quantification compared with placenta from the control group.