In a placebo-controlled, double-masked clinical trial, the authors evaluated the effects of topical 2% cyclosporine on 20 patients with vernal keratoconjunctivitis (VKC). Nineteen patients were male and one was female. Patients ranged in age from 5 to 19 years (mean, 9.7 years). Symptoms of itching, tearing, photophobia, discharge, and foreign body sensation were evaluated and recorded at weekly intervals for a period of 6 weeks. There was a statistically significant decrease in the conjunctival hyperemia, papillary hypertrophy, punctate keratitis, and Trantas' dots in the group of patients treated with cyclosporine but not in the group treated with placebo. No adverse effects and no detectable levels of cyclosporine were noted in the blood in the cyclosporine-treated group. Cyclosporine appears to be safe and effective for the short-term treatment of VKC.