The paper investigates blood flow in microfluidic devices manufactured using soft photolithography, simulating vascular stenosis with different constriction parameters. It was found that with a constriction of 50 μm width, erythrocytes are significantly accelerated, and at 200 μm the flow is more uniform. Tandem stenoses demonstrate a "streamlined" zone between constrictions, increasing with increasing distance between them. The results can be used to model blood flow and develop methods for diagnosing vascular pathologies. Keywords: microfluidic device, stenosis, blood, erythrocyte.