To examine the relationship between intra-access pressures and vascular stenosis, we measured the total (pT) and static (pS) pressures and the severity of stenosis before and after percutaneous transluminal angioplasty (PTA). The dynamic pressure (△p) and static intra-access pressure ratios (SIAPR) were calculated. We analyzed the clinical correlation of △p and SIAPR with the severity and location of stenosis, and searched potential predictive factors for the severity of stenosis using multivariate regression. While SIAPR was significantly decreased only in outflow stenosis after PTA (p < 0.0001), △p was significantly increased in both inflow and in outflow stenosis (p < 0.05). SIAPR was negatively correlated with the severity of stenosis only in outflow stenosis (p < 0.0001), and △p was significantly correlated with both inflow and outflow stenosis (p < 0.05). △p was an independent predictor for the severity of stenosis in both inflow and outflow stenosis (p < 0.05). Thus, our study suggests that △p may be more clinically useful than SIAPR not only in detecting access stenosis regardless of its location, but also providing information about the severity of stenosis.