The permeability of the blast furnace and in particular of its lower part, conditions its performances and its campaign duration. It is therefore essential to be able to characterize it. Several methods have already been used as radioactive tracing, coke core boring and Iiquids sampling, achieved by the tuyere probe installed on the BF 1 of Sollac Fos. Results of these measurements can be completed by gas analyses on the blast furnace radius and by gas tracing using helium, also achieved with the tuyere probe. This article presents the synthesis and shows the consistency of these various measurements.