AbstractTwo metachromatic dyes, safranin O and toluidine blue O, were utilized to study glycosaminoglycan content and topographical distribution in histological sections of normal articular cartilage obtained from young adult New Zealand white rabbits and from human aged and osteoarthritic cartilage specimens. Toluidine blue (acetate buffer, pH 4.0) was superior to safranin O (buffered or aqueous) in delineating differences in metachromasy between pericellular and interterritorial regions of articular cartilage. The reproducibility of staining between serial sections from the same tissue specimen was found to be a function of tissue section thickness. Below 8μ, modest to significant variability in metachromatic staining was observed. Sections cut at 8–10μexhibited superior reproducibility in staining intensity.