Previous studies have shown the effectiveness of topical cromolyn solution in the treatment of allergic conjunctivitis. However, the preservative, phenylethanol, produces an immediate burning or stinging sensation when the drops are first instilled in the eye. A double-blind, crossover, placebo controlled study using 2% cromolyn solution was conducted, without the preservative and supplied in unit doses. Twenty six patients took part in the trial. They had ragweed pollen-induced conjunctivitis. The results of the trial indicate that the active drug was effective in controlling the signs and symptoms of allergic conjunctivitis in 22 of the 26 patients, i.e., 84.6% (p less than 0.001). Two patients preferred the placebo. There were no complaints of stinging or burning sensation after the instillation of the drops in the eyes. There were no cases of infection of the eye. Without the preservative, the cromolyn solution does not damage the soft contact lens.