We adapted a previously described procedure to quantitate collagen in corneal tissue sections prepared from paraffin-embedded samples. The method entailed staining the deparaffinized tissue sections with Sirius red, eluting the bound dye with NaOH-methanol, and estimating the color in a spectrophotometer as an indication of the collagen content. This simple, rapid and reproducible method is comparable to biochemical assays and can be applied to study various corneal specimens readily available from eye pathology laboratories.We examined corneal sections from patients with aphakic bullous keratopathy, pseudophakic bullous keratopathy, Fuchs' dystrophy and lattice corneal dystrophy with this method. No significant difference in collagen staining was found between these pathologic specimens and normal control tissues. Biochemical assays also confirmed these findings. Sections from patients with macular and granular corneal dystrophies showed reduced staining suggesting a possible alteration in collagen content. This possibility, however, was not supported by data from biochemical analysis.