This document specifies a method for sampling fabric filter medium from a filter system in operation, and a test method for evaluating the degradation of the sampled filter medium. It applies to both woven and nonwoven fabric filter media. This document specifies a method for removing used filter medium from a dry type filtering dust collector, a method for removing dust from the sampled filter medium as part of preparation for testing, and measurement parameters for the test specimen. The number of filter elements to be sampled, their positions in the blocks of filter elements in the dust collector, the position and the size of the test specimens to be cut out from the filter element, measurement parameters and their test methods are also specified. This document also specifies a storage and transportation method for the sampled filter medium that will protect the health of workers and people conducting the tests.