Many nasal sprays used in the treatment of rhinitis contain a steroidal agent, giving rise to fear of side effects when they are used frequently and continually. Accordingly, we undertook the development of a nasal spray containing oxaprozin, a nonsteroidal anti-inflammatory agent. Suitable discharge pressure and surfactants were determined by applying trial aerosols to human subjects in "feeling" tests to assess approval rating. Other tests showed that about 80% of the expelled oxaprozin was released into the nasal cavity, and that the chosen formulation caused only a low level of irritation to the nasal mucosa. Most of the aerosol particles were found to adhere to Kiesselbach's area and the frontal region of the inferior concha, which are the major areas where inflammation and nasal haemorrhage occur. When the nasal spray was administered to 50 patients, a sufficient therapeutic effect was achieved, especially in the treatment of nasal haemorrhage, and side effects have not yet been detected.