The objective of our study was to measure the blood permeability of commercially available non-woven surgical gowns (a trilayer spunbond/meltblown/spunbond (SMS) polypropylene and a hydroentangled pulp/polyester) when subjected to conditions likely to be incurred in a surgical setting. Based on the application of a form of Darcy's Law, a simple filtration test was developed to measure the permeability of blood barriers to human whole blood over time. Results indicate that the two gowns respond differently to an applied pressure of 25 mmHg, which simulated a pressure generated during a pressing or leaning motion which could occur in an operating room. The permeability of the SMS gown exhibited an initial value (4.17 ± 2.41 μl/min-cm2) which decreased to 0.85 ± 0.17 μl/min-cm2, yet then increased, approaching the initial value, over time. The permeability of the hydroentangled gown decreased from an initial value (195.47 ± 38.62 μl/min-cm2) to a final value (41.21 ± 8.65 μl/min-cm2) over time. We conclude that fouling of pores with cellular material may attribute to the changes in the permeability of the hydroentangled gown. However, changes observed in the SMS gown's permeability may be due to a blood/material interaction, such as change in the hydrophobicity of the gown, which lead to an increased permeability over time. Pore fouling may partly account for the initial decrease in permeability of the SMS gown.