The Purpose of this study is to evaluate the safety and efficacy of MP03-36 (0.15% azelastine hydrochloride)at dosages of 2 sprays per nostril once daily and 2 sprays per nostril twice daily in patients with seasonal allergic rhinitis.

Inclusion Criteria:

• Male and female patients 12 years of age and older
• Provide written informed consent/pediatric assent. If the patient is a minor, a parent or legal guardian must give written informed consent
• Screening Visit: Have a 12-hour reflective total nasal symptoms score ( TNSS) of at least 8 out of a possible 12 and a congestion score of 2 or 3 on Day -7
• Randomization Visit: Have a 12-hour reflective total nasal symptoms score (TNSS) (AM or PM) of at least 8 on 3 separate assessments (one of which was within 2 days of Day 1, and can include the morning of Day 1) during the Lead-in Period. In addition, an AM or PM nasal congestion score of 2 or 3 must have been recorded on 3 separate assessments (one of which was within 2 days of Day 1, and can include the morning of Day 1).
• Must have taken at least 10 doses of study medication during the lead-in period
• Randomization Visit: An instantaneous (TNSS) of ≥ 8 before beginning the onset of action assessment on Day 1
• Willing and able to comply with the study requirements
• At least a 2-year history of seasonal allergic rhinitis (SAR) during the fall pollen allergy season
• The presence of IgE-mediated hypersensitivity to local fall pollen confirmed by a positive response to either skin prick or intradermal testing within the last year. A positive response is defined as a wheal diameter of at least 3 mm larger than the control for the skin prick test or at least 7 mm larger than the control for the intradermal test.
• General good health and free of any disease or concomitant treatment that could interfere with the interpretation of the study results as determined by the investigator or the sponsor's medical officer
• Patients receiving immunotherapy injections (antigen desensitization) must be on a stable maintenance regimen for at least 30 days before the first study visit (adjustments to regimen following a brief period of missed injections does not preclude participation). Patients who are on maintenance doses of sublingual immunotherapy may be considered for the trial on a case-by-case basis after discussion with the sponsor's medical monitor or designee.

Exclusion Criteria:

• The use of any investigational drug within 30 days prior to Day -7. No investigational products are permitted for use during the conduct of this study
• Presence of any hypersensitivity to drugs similar to azelastine and to either sorbitol or sucralose (Splenda® brand sweetener)
• Women who are pregnant or nursing
• Women of childbearing potential who are not abstinent and not practicing a medically acceptable method of contraception
• Respiratory tract infections within two weeks prior to Day -7
• Respiratory Infections requiring oral antibiotic treatment two weeks prior to Day -7
• Other nasal disease(s) likely to affect deposition of intranasal medication, such as sinusitis, rhinitis medicamentosa or clinically significant polyposis or nasal structural abnormalities
• Patients with asthma (with the exception of mild, intermittent asthma)
• Patients with significant pulmonary disease
• Patients with a known history of alcohol or drug abuse
• Existence of any surgical or medical condition, which in the opinion of the investigator or sponsor, might significantly alter the absorption, distribution, metabolism, or excretion of study drug
• Clinically relevant abnormal physical findings within 1 week of randomization which, in the opinion of the investigator, would interfere with the objectives of the study or that may preclude compliance with the study procedures
• Planned travel outside the study area during the study period
• Family members and employees should be excluded
• Patients who received prohibited medications within specified timepoints in the protocol.