Topical fibronectin was evaluated for the treatment of keratoconjunctivitis sicca in a multicenter, double-masked, controlled study in which 272 patients were randomly assigned to treatment. Patients with documented clinical evidence of keratoconjunctivitis sicca received either fibronectin, a vehicle alone, or a commercially available artificial tear. Evaluation at baseline, 21, 42, and 63 days consisted of patient self-evaluation of symptoms, rose bengal and fluorescein staining, tear breakup time, Schirmer's testing, and conjunctival impression cytology. Although all groups showed improvements in most study variables during the course of the study, there were no statistically significant differences found between any of the groups. Topical fibronectin does not appear to be more effective than artificial tears in the treatment of keratoconjunctivitis sicca.