en <p>Background: Proteolysis imbalance can result in infertility. The purpose of the current study was to investigate the function of kininogen, neutrophil elastase, trypsin-like proteases, &alpha;1-protease inhibitor (&alpha;1-PI), and &alpha;2-macroglobulin (&alpha;2-MG) in blood, saliva, and follicular fluid as an indicator of the success of in vitro fertilization (IVF).<br /> Methods: In general, twenty-one women undergoing an IVF cycle, as well as a control group consisting of ten healthy women, were included. The proteinase activity was measured by the rate of hydrolysis of specific substrates. The proteinase inhibitor activity was determined by the intensity of trypsin inhibition. The analysis was conducted using R software (version 4.4.1). The significance level was set at p&lt;0.05.<br /> Results: In women with infertility, blood activities of neutrophil elastase, &alpha;1-PI, and &alpha;2-MG were elevated, whereas kallikrein and prekallikrein activities were decreased, compared with controls. In follicular fluid, neutrophil elastase activity increased 3.4-fold, &alpha;1-PI 1.8-fold, and &alpha;2-MG 5.6-fold, whereas prekallikrein decreased by 85%, compared with women who had been infertile for fewer than five years (p&lt;0.05). During pregnancy, kallikrein and &alpha;1- PI levels in follicular fluid were low, and unsuccessful IVF was associated with higher trypsin-like protease activity and an increased kallikrein/&alpha;1- PI ratio.<br /> Conclusion: High elastase- and trypsin-like proteinase activity, along with elevated &alpha;1- PI and &alpha;2- MG levels in blood was associated with IVF benefits. Salivary kininogenase and &alpha;2-MG can be early prognostic indicators for IVF outcomes.</p> Follicular fluid, In vitro fertilization, Saliva, Serine proteases, α1-protease inhibitor, α2-macroglobulin 57 70 https://www.jri.ir/article/140301 /documents/fullpaper/en/140301.pdf LiudmilaSpirinaDepartment of Biochemistry and Molecular Biology, Siberian State Medical University, Tomsk, Russian Federation spirinalvl@mail.ru123008OlgaAkbashevaDepartment of Biochemistry and Molecular Biology, Siberian State Medical University, Tomsk, Russian Federation 123009DenisDyakovDepartment of Biochemistry and Molecular Biology, Siberian State Medical University, Tomsk, Russian Federation 123019KseniaKudisovaDepartment of Biochemistry and Molecular Biology, Siberian State Medical University, Tomsk, Russian Federation 123011EkaterinaRomanovaDepartment of Biochemistry and Molecular Biology, Siberian State Medical University, Tomsk, Russian Federation 123012KiraSidorenkovaDepartment of Obstetrics and Gynecology, Siberian State Medical University, Tomsk, Russian Federation 123013IlyaPetrovDepartment of Obstetrics and Gynecology, Siberian State Medical University, Tomsk, Russian Federation 123014IuliiaSamoilovaDepartment of Pediatrics with a Course in Endocrinology, Siberian State Medical University, Tomsk, Russian Federation 123015EvgenyMerkulovDepartment of Biochemistry and Molecular Biology, Siberian State Medical University, Tomsk, Russian Federation 123016DianaShilovaDepartment of Biochemistry and Molecular Biology, Siberian State Medical University, Tomsk, Russian Federation 123017MarinaStakheevaDepartment of Biochemistry and Molecular Biology, Siberian State Medical University, Tomsk, Russian Federation 123018