The objective of this study was to develop and test a health-related quality of life questionnaire for clinical trials in rhinoconjunctivitis. The Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) was developed by asking patients to identify areas of their lives affected by rhinoconjunctivitis. The resultant RQLQ was tested for reproducibility, responsiveness and validity in a randomized, double-blind trial of regular versus 'as required' aqueous beclomethasone dipropionate (BDP) nasal spray in ragweed pollen-induced rhinoconjunctivitis. Eighty-five patients from previous rhinoconjunctivitis studies participated in the developmental survey. Sixty ragweed-sensitive patients, from previous trials and media notices, were enrolled in the clinical trial. Aqueous BDP (800 micrograms) nasal spray was administered regularly or 'as required' throughout the ragweed pollen season. The survey revealed that, in addition to local symptoms of rhinoconjunctivitis, patients experienced impairment of quality of life through systemic symptoms, sleep disturbance, practical problems, activity limitations and emotional problems. The RQLQ includes 28 questions related to these dimensions. Repeated administration of the RQLQ demonstrated good reproducibility. During the clinical trial, the RQLQ proved responsive in its ability to distinguish between regular and 'as required' medication use. Validity was shown by moderate to strong relations between changes in symptom diary scores and changes in RQLQ scores. In conclusion the RQLQ is likely to prove useful as a measure of health-related quality of life in clinical trials in both rhinoconjunctivitis and rhinitis.