Past experiments made on the influence of fatliquoring on the physical properties of leather can be questioned from the standpoint of statistical principles. As a basis for studying and clarifying the influence oil has on the physical properties of leather, statistically designed experiments were carried out comparing the physical properties of fatliquoring leather to solvent extracted leathers. Such physical tests as tensile strength, stitch tear strength, tongue tear strength, ball burst strength, and hysteresis curves were conducted and the data analyzed. A discussion of the results is presented and emphasis placed on those tests that best distinguish what the fatliquor does to the leather.