Cyclosporine (cyclosporine A, CsA) is a selective immunosuppressant that inhibits T-cell activation. Its systemic use in the treatment of various ocular diseases has been successful. Topical CsA 2% was used in noncontrolled groups of seven patients with high-risk corneal transplants, two with peripheral corneal melting syndrome, three with chronic vernal keratoconjunctivitis, and two with ligneous conjunctivitis. Six (85%) of the seven high-risk corneal transplants remained clear after an average follow-up of 12 months (range, 10-15 months). Two (67%) of the three patients with chronic vernal conjunctivitis showed dramatic improvement in signs and symptoms after three months of therapy, but recurrence was the rule after the withdrawal of the drug. Peripheral corneal melting syndrome and ligneous conjunctivitis appeared to be refractory to topical CsA use. Systemic CsA levels were measured in all patients.