The authors performed fibronectin studies on scleral specimens derived from a patient with nanophthalmos. Immunohistochemical staining with antifibronectin was conducted using both formaldehyde-fixed, paraffin-embedded tissue sections and unfixed tissue-cultured scleral cells. In each case, the nanophthalmic samples exhibited fibronectin staining stronger than that obtained from normal human subjects. Results from an enzyme-linked immunosorbent assay (ELISA) confirmed the histologic findings that, in tissue culture, the patient's scleral cells contained and secreted a higher amount of fibronectin than did the normal control cells. The elevated fibronectin level may be related to the development of nanophthalmos.