Cyclosporine eyedrops 2% have been used for treatment of corticosteroid-resistant vernal keratoconjunctivitis (VKC) cases. The purpose of our study was to verify the efficacy of 1.25% vs. 1% topical cyclosporine in improving severe form of VKC in childhood. Twenty children with severe VKC, were enrolled in a double-blind, placebo-controlled study and received cyclosporine 1.25% in one eye for 2 wk. Then an open trial was conducted during the next 3 months and 2 wk. Thirty-two more patients were recruited the next year into a new open trial and they received cyclosporine 1% for 4 months. Ocular subjective symptoms and objective signs were scored in all children at entry, 2 wk and 4 months. Skin prick tests and conjunctival scraping tests were also performed; serum immunological and biochemical markers were assessed. The mean score values for severity of subjective symptoms and objective signs were significantly decreased after 2 wk, and 4 months, compared with those at entry (p < 0.001), in both groups of children who received cyclosporine eyedrops 1.25% and 1%, respectively. Serum markers did not differ from the beginning to the end of treatment. Conjunctival eosinophils and cyclosporine serum levels were not detectable at the end of therapy, nor were endothelial corneal cells damaged. Our findings suggest that 1% cyclosporine concentration might be the minimal effective treatment regimen to control symptoms and local inflammation in severe forms of VKC.