Ovarian hyperstimulation syndrome (OHSS) is a severe assisted reproductive technology complication, the study of whose pathogenesis is still in progress. There are no ways to prevent OHSS in each specific patient. Therefore, to determine the level of a risk for the syndrome is one of the research priority areas. Objective: to assess the role of renin-angiotensin-aldosterone system (RAAS) and nitric oxide metabolism gene polymorphisms in the development of OHSS. Material and methods. A comparative prospective cohort study of the role different factors in the development of OHSS was conducted in 70 women undergoing in-vitro fertilization or intracytoplasmic sperm injection. Molecular genetic examination of 6 polymorphic variants of 5 genes responsible for the regulation of the components of RAAS and nitric oxide metabolism was made in all the women. Results. The examination revealed that the patients with OHSS had the following statistically significant combinations of genotypes of the polymorphic RAAS genes and a marker for the NOS3 gene: AGT 704 CC + AGTR2 1675 AA and AGT 704 CC + NOS3 894 GT.