The collagen arrangement of different cartilages of several mammals was studied by the Picrosirius-polarization method applied to tissue sections whose proteoglycans had been previously removed by enzymatic digestion. This procedure not only increases collagen birefringency but it also enhances the optimal resolution, permitting an accurate observation of the collagen disposition in this tissue. Our observations led to the conclusion that in the material studied at least five general patterns of collagen arrangement occur. When studied with the aid of electron microscopy, different cartilages showed variable values in their collagen fibril diameter. The results obtained suggest a greater variability in the collagen fibril diameters of those cartilages submitted to strong pressures.