Objective: Exposure to indoor allergens during childhood has been associated with an increased risk of sensitization. There is no data about indoor allergen levels in day-care centers in Turkey. We hypothesized that day-care centers (DC) would be relevant sources of cat and mite allergens. Material and Methods: Fifty-seven dust samples were collected from 19 DCs in Izmir, their gardens, and classrooms of the primary schools where the DCs are located in. A questionnaire about characteristics of DCs was completed. Fel d 1, Der p 1 and Der f 1 allergen levels were quantitated by enzyme-linked immunoassay. Results: Fel d 1 was detected in all, and mite allergens in 94.7% of the samples. Levels exceeding sensitization threshold level for cat and mite allergens were present in 73.7%, and 21.1% of DCs, respectively. Fel d 1 levels exceeding threshold level that might cause asthma exacerbation was detected in 21% of DCs. Fel d 1 levels in DCs and their gardens were higher than the classrooms of the same school. Der f 1 levels were identical in DCs, gardens and classrooms. Der p 1 concentration was higher in DCs with air-conditioning, than DCs without a ventilation system. Although there was no difference for Fel d 1 levels in DCs with or without carpeted floor, Fel d 1 concentrations in DCs with carpet were significantly higher than in classrooms with no carpet. Conclusion: Day-care centers in Izmir are important sources of indoor allergens that could cause sensitization or even allergic symptoms in children and their staff.