The presence of sinusitis has been found out 85 times out of 278 cases of acute relapsing respiratory diseases in children between 4 and 12 years of age. The maxilla sinuses have been those most frequently stricken; the frontal sinuses come next and last at a distance the sphenoidal sinus. A close relationship between the entity of basic respiratory pathology and the presence and seriousness of the sinusitis has been observed. There also seems to be a rather close relationship between the frequency of the presence of sinusitis in children with respiratory pathology either relapsing or chronic and climatic environmental situation. A damp climate with persistent fog together with industrial atmospheric pollution seems to favour the considered pathology in an undisputed way.