Cystic fibrosis (CF) is a genetic disease caused by mutations in the cystic fibrosis transmembrane regulator (CFTR) gene resulting in absent or deficient expression and function of CFTR protein. It has recently been reported that CFTR may also be involved in the apoptotic process of epithelial cells. In this study we examined the expression of Fas on conjunctival epithelial cells and the serum and tear fluid concentrations of soluble Fas (sFas) in patients with cystic fibrosis. This article studied 25 patients with CF and 25 normal subjects. Conjunctival epithelial cells were obtained by impression cytology, and processed and analyzed for flow cytometry. The amount of sFas in serum and tear fluid was measured by enzyme-linked immunosorbent assay (ELISA). The analysis of Fas expression showed significant increases in the CF patients compared with the control group (P = 0.000012). There was no difference in the concentration of serum and tear fluid sFas between CF patients and controls (P = 0.0515 and P < 0.05, respectively). Fas expression in cystic fibrosis conjunctival epithelium could play an important role in controlling local inflammatory cell apoptosis and may confirm the role of Fas in maintaining ocular immune privilege.