Sublingual immunotherapy (SLIT) for allergic rhinitis is commonly used in Europe, but not in Japan. Although some studies of SLIT for Japanese cedar pollinosis (JCP) were reported, all the subjects were adults. SLIT is an ideal treatment for children rather than for adults, because it overcomes subcutaneous immunotherapy in the complication of painful injections and habitual visits of a hospital. We tried an open pilot study of SLIT for pediatric JCP.Ten pediatric patients with JCP (4 boys and 6 girls, mean ages; 8.5+/-2.2 years old) were treated according to a scheduled doses of SLIT with a therapeutic standardized Japanese cedar pollen extract. They were maintained at the doses of 2000JAU of allergen once a week during pollen scattering. Clinical efficacies during the pollen scattering in the first season were evaluated from their diary of symptoms and medications, visual analog scale (VAS) of symptoms, and a questionnaire for SLIT.The mean severity scores of nasal and ocular symptoms were low. VAS was also very short. Three of 10 patients had no symptoms without any drugs during the pollen season. Two patients were medicated within 5 days.SLIT was effective for pediatric Japanese cedar pollinosis.