The clinical effect and tolerance of momethasone furoate (MF) glucocorticoid nasal spray (MFNS) were studied in 14-70 year-old patients suffering from seasonal allergic rhinitis. The patients administered daily one (morning) dose, 100 micrograms each, of MF into both nostrils, for a period of 14 days. They did not use other medicines affecting nasal symptoms. Nasal symptoms (nasal discharge, nasal obstruction, nasal itching, sneezing) and non-nasal symptoms (lacrimation, eye itching/burning sensation, palatal itching, ear itching, general itching), scored 0 to 3, and serving as a basis for evaluating the effect, were registered before treatment (day 1) and at visits on 3, 7 and 14th day. Of the 196 patients involved in the open multicentric study, 188 completed the study. The total average nasal symptom scores decreased, already after 3 days of treatment, from 8.7 to 4.1 and to 1.6 by the 14th day. Decrease of non-nasal symptoms was also conspicuous, however, lacrimation persisted in 57 of 188 cases, while eye itching--mainly in moderate and mild form--in 90 cases. The general condition of rhinitis before the treatment was evaluated by the examiners as severe or very severe in 155 cases (82%), as symptom-free (99 cases) on day 14 in, and mild (71 cases), in 170 cases (90%). The therapeutic effect was considered by both, patients and physician, as excellent, in 106 (56%) and 115 (61%) cases, resp. and as good in 63 (34%) and 56 cases (30%). Side-effects were mostly mild and transitory. Treatment was not discontinued due to side-effect in any of the cases. Based on the results, MFNS, administered in a single daily dose of 200 micrograms, has proved to be an effective and safe glucocorticoid preparation, also easy to use locally, in the treatment of allergic rhinitis.