The authors made a study of the antihistaminic properties of Pipoxizine in 20 subjects with proven histaminic hyperreactivity. The design of the trial consisted in comparing the changes of VC, FEC1, expiratory airway resistance and V50 produced by a histamine aerosol given before and after administration of Pipoxizine. Pipoxizine was given by mouth to 10 patients and intravenously to the other 10 of the group. The statistical analysis of the results demonstrated an antagonist effect of Pipoxizine on the histamine induced bronchoconstriction. The data of this trial are confirmative of the results of other experimenters. It seems therefore reasonable to take into consideration the use of Pipoxizine in the preventive treatment of the paroxystic attacks of the asthmatic disease.