A project of a humanitarian action was preceded by a health diagnosis of a population in the rural district Bonou in Bénin. A diagnosis of perception was set up by the interviews among the population and the local health professionals. That diagnosis was completed by an objectified diagnosis originating from the analysis of 460 consultations performed in Bénin end 1998- beginning 1999. The cross-sorting between the diagnosis of perception and the objectified diagnosis pointed out four public health problems: malaria, bronchial asthma, infectious diarrhoeas and Buruli ulcer with respective prevalences of 9%, 6%, 3% and 0.9%. The prevalence of bronchial asthma fluctuates from 4% in dry areas to 8% in wet areas (Chi 2 = 3.50; p = 0.06). The role of house dust mites is suspected because of those ecological arguments to which is added clinical reasoning. Bronchial asthma was chosen as a priority health problem because of the feasibility and acceptance of a survey which aims at pointing out the allergic etiology. The confirmation of that etiology will enable in that case the decrease of the allergenic pressure, particularly well adapted solution in the Southern countries. Therefore a humanitarian action is foreseen to apprehend the etiologies of bronchial asthma in the rural district Bonou in Bénin in 2000.