The purpose of this study is to investigate the safety and effectiveness of ciclesonide nasal spray as compared with placebo (inactive substance) nasal spray in relieving symptoms of seasonal allergic rhinitis caused by pollen. Ciclesonide will be administered once during the exposure to ragweed pollen in a controlled environment. The study duration consists of a baseline period (up to 5 days) and a treatment period (1 day). The study will provide further data on safety and tolerability of ciclesonide.

Main Inclusion Criteria:

• Written informed consent
• General good health
• History of SAR to short ragweed pollen for 2 years immediately preceding the study
• Demonstrated sensitivity to short ragweed known to induce SAR through a standard skin prick test

Main Exclusion Criteria:

• Clinically significant physical finding of nasal anatomical deformities causing greater than 50% obstruction, including but not limited to nasal polyps, septal defects, respiratory tract malformations, nasal trauma or surgery
• Known hypersensitivity to any corticosteroid
• History of a respiratory infection or disorder including but not limited to bronchitis, pneumonia, chronic sinusitis, influenza or SARS (severe acute respiratory syndrome) within 14 days preceding the Screening Visit
• History of alcohol or drug abuse within 2 years preceding the Screening Visit
• Active asthma requiring treatment of inhaled or systemic corticosteroids and/or routine use of beta-agonists or any controller drugs
• Use of antibiotic therapy for acute conditions within 14 days preceding the Screening Visit
• Exposure to systemic corticosteroids for any indication, chronic or intermittent within 60 days preceding the Screening Visit