This study investigated the relation between mould exposure and allergic rhinitis in Istanbul through questionnaires and measurements of fungal propagules in indoor air. The study group was 42 patients with perennial allergic rhinitis who were sensitive to mould and 40 age and sex matched healthy subjects as controls. A questionnaire was used to characterise the variables of home environment and occupants' behaviour which might have an impact on the presence of fungal levels. At the same time, symptom scores were assessed according to the answers of the patients while air samples were collected to obtain a comparison between the patients' symptoms and the fungal counts. Samples were collected from the bedrooms and the main living rooms between 15 September and 15 November, 2002. Fungal concentrations were reported as colony forming units per cubic metre of air using the MAS 100 conversion unit table. The questionnaires showed that patients reported significantly higher dampness, mould and mildew in their homes than the controls (p=0.004, p=0.02, respectively). Also the relative humidity in the patients' houses was significantly higher compared to the controls (p<0.001). The total culturable concentrations of fungi were significantly higher in the patients homes compared to those in the homes of the controls (p = 0.003, p = 0.009, respectively). A significant positive correlation was found between the patients' symptom scores and the fungal propagule concentrations (r(2) = 0.39-0.49, P<0.001). Overall the results of this study suggest that damp housing and indoor fungal concentrations show a positive correlation with symptoms of allergic rhinitis.