Analyses of test results from interlaboratory tests on extractable matter in wool are reported. A total of ten laboratories were involved in the test that aimed at ascertaining the effect of specimen size, solvent temperature, length of extraction time, and specimen moisture content on the amount of extractable matter. Multiple dependent variable regression analysis of the results using the percentage of extractable matter as a dependent variable showed this to be inversely related (P < 0.01) to specimen size. Extraction time appeared to have some influence, although the relationship was not significant (P > 0.05). It is concluded that the extraction method needs to be revised to specify specimen size.