Not only the aetiology and the pathogenesis, but also the ecology of the house-dust system, determine the symptoms of house-dust allergy. In interpreting the symptoms, the altered elasticity of nasal blood vessels as a sign of allergic and non-allergic rhinitis must be taken into consideration.--Excerpts from a questionnaire are used to describe patients' complaints: They experienced stuffines of the nose for half an hour or longer in the morning with a lessening of symptoms in the evening--a condition which had existed for months or even years. These complaints are compared to the results of a scratch test in which the patients' own house-dust was used. With a statistical certainty of more than 99%, the described complaints differed from those of a perennial and constant rhinitis of a differing aetiology. The value of a special anamnesis in association with dermatological and intranasal tests is discussed.