The effect of an orally applied calcium preparation (Frubiase Calcium forte) was investigated and compared with a placebo in 20 adolescent patients submitted to a random double-blind test on the immediate allergic reaction. The prick test with histamine and grass pollen mixed extract showed a highly significant statistical decrease (p less than 0,001) of wheal extension after an oral dose 1 x 6 Frubiase Calcium forte fluid ampoules, when compared to the test before application.