OBJECTIVE: Individuals with seasonal allergic rhinitis (SAR) experience symptoms that can have a detrimental impact on their quality of life (QOL). Clinical trial guidelines require that QOL questionnaires be cross-culturally validated for use in different ethnic populations. Therefore, the aim of this study was to validate Japanese translations of the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) and the Work Productivity and Activity Impairment – Allergy Specific (WPAI-AS) questionnaire. METHODS: This 2-week psychometric validation study assessed 200 Japanese patients with SAR defined by a Total Symptom Score (TSS) ?12 out of 20 at entry. Patients completed demographic information, the RQLQ (28 questions to assess the impact of symptoms on activities), the WPAI-AS (nine questions to assess effects on work/classroom performance/attendance), the SF-36 (Short-Form 36, a generic QOL assessment) and TSS assessments (sneezing, runny nose, nasal congestion, ocular itching, lacrimation, nasal itching; on a 5-point Likert scale) on study entry and 7 days later. The validity of the questionnaires was tested through construct validity, analysis of floor/ceiling effects, reliability (internal consistency/reproducibility), validity (concurrent/clinical) and responsiveness. RESULTS: The RQLQ demonstrated adequate construct validity, was internally consistent, satisfied the minimum reliability coefficient of 0.7 for each scale, showed excellent discrimination between clinical severity (defined by TSS) and correlated with clinician’s ratings of symptoms/impairment. The WPAI-AS discriminated between clinical severity and correlated with clinician’s ratings of symptoms/impairment. Both tools demonstrated adequate concurrent validity with the SF-36 and acceptable reproducibility. The RQLQ was responsive to changes in symptom status and WPAI-AS was responsive for impact scales. CONCLUSION: The results of this psychometric evaluation show that the Japanese translation of the RQLQ and WPAI-AS questionnaires are valid and reliable tools for assessing the impact of SAR symptoms on patients' health-related QOL and should therefore be considered as valuable measures for clinical studies in Japan.