Inhalation and nasal aspirin challenge has been investigated in asthma patients with co-existing rhinitis. Eight of 39 asthma patients were diagnosed as aspirin-sensitive on the basis of inhalation challenge. Seven aspirin-sensitive asthmatics were subjected to nasal aspirin provocation. During nasal challenge, all seven patients experienced a fall in FEV1 of at least 15%, two showed a significant increase (greater than 400%) in nasal airways resistance (NAR) and one developed urticaria. No significant changes in FEV1 or NAR were observed in nine normal subjects after aspirin inhalation and nasal challenge. There were no significant changes in FEV1 or NAR in six aspirin-tolerant asthmatics when aspirin was given intranasally. The results of this study show that aspirin nasal provocation impairs lung function in aspirin-sensitive asthmatics. In comparison with inhalation challenge responses are generally milder and easier to control. Nasal challenge is also less time-consuming than other methods of aspirin challenge and is therefore more suitable for routine use.