Background: Food hypersensitivity (FH) affects 1-2% of the adult population and is more common in atopic individuals. The aim of this study was to determine the frequency of FH and risk factors for its development in patients with seasonal rhinitis (SR) in our allergy clinic. Methods: We performed a retrospective study based on the medical records of 774 patients out of 955 patients diagnosed with SR in an adult allergy clinic between 1 January 1991 and 31 December 2003. Results: The mean age of the patients was 29.1 ± 9.29 and 62.7% were females. The most common major complaints were due to nasal symptoms in 82.3%. The mean duration of SR was 6.8 ± 6.8 years. Patients were symptomatic for a mean of 3.5 ± 1.7 months per year. Skin prick tests (SPT) with common aeroallergens were positive in 685 patients (90.3%), and the most common sensitivity was against timothy (85.1%). The most common accompanying allergic disease was FH in 14%. FH according to history and the results of SPT performed with food allergens were discordant. The most common clinical manifestations of FH were oral allergy (49.1%) and cutaneous symptoms (38.9%). Risk factors for the development of FH in patients with SR were dermatological symptoms, rhinitis duration > 5 years, symptom duration > 3 months per year, SPT reactivity to Artemisia vulgaris, tree pollen allergens (Corylus avellena, Betula verrucosa), and bee allergy. Conclusion: FH was the most common (14%) accompanying allergic disease in patients with SR. SPT with food allergens have limited diagnostic value for food allergy and/or intolerance. Risk factors for developing FH in patients with SR in Turkey were dermatological symptoms, duration of rhinitis > 5 years, duration of rhinitis symptoms > 3 months per year, and SPT reactivity to Corylus avellena.