Seasonal allergic rhinitis (SAR) exerts a significant adverse impact on health-related quality of life (QoL) and productivity of those who suffer from it. Unfortunately, some therapies for SAR also have a negative impact. Therefore, it is important to scrutinize the influence of new SAR therapies on patients' QoL and ability to function. The purpose of this study was to evaluate the effect of a new nasal antihistamine, olopatadine, on QoL in SAR patients. In a multicenter, randomized, double-blind SAR study comparing olopatadine 0.6 and 0.4% to placebo nasal spray, patients completed the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) at baseline and after 2 weeks of treatment. The RQLQ is a validated questionnaire that addresses overall QoL and 7 domains of impairment associated with rhinoconjunctivitis (activities, sleep, non--nose/eye allergy symptoms, practical problems, nasal symptoms, eye symptoms, and emotional impairment). The overall RQLQ mean changes from baseline with olopatadine 0.6% (-1.1 +/- 1.4) and 0.4% (-1.1 +/- 1.3) nasal sprays were superior (p < 0.05) to placebo (-0.8 +/- 1.2). Olopatadine spray 0.6% was superior to placebo in six of the seven RQLQ domains and olopatadine 0.4% was superior to placebo in five RQLQ domains (p < 0.05). The correlation between the olopatadine 0.6% mean total symptom scores and mean RQLQ score was r = 0.66 (p < 0.0001), indicating that the enhancement in QoL derived from olopatadine therapy was significantly associated with symptom reduction. Olopatadine nasal spray is an effective antiallergy medication that significantly improves the QoL of patients suffering from SAR.