Seasonal allergic rhinitis (SAR) is common in adolescents. However, few studies have investigated the effectiveness of intranasal corticosteroids (INSs) for nasal and ocular symptoms of SAR solely in adolescents. The purpose of this study was to determine the safety and efficacy of the INS mometasone furoate nasal spray (MFNS) in adolescents; a post hoc analysis was conducted of adolescents who had participated in a study with adults. Data were analyzed retrospectively for subjects aged 12-17 years with moderate or severe SAR randomized to mometasone furoate, 200 mcg once daily (n = 86), or placebo (n = 82) for 15 days in a multicenter, double-blind, placebo-controlled study. Symptom scores (0 = none to 3 = severe) were recorded in diaries twice daily. End points included changes from baseline in total nasal symptom score (TNSS), individual nasal symptom score (rhinorrhea, congestion, itching, and sneezing), and total ocular symptom score (TOSS). Over 15 days, a significantly greater decrease from baseline in mean TNSS was observed in subjects receiving mometasone furoate (-2.47; -28.8%) compared with those receiving placebo (-0.9; -9.6%; p < 0.001). Significant improvement versus placebo was seen for each full day of treatment. Mometasone furoate significantly improved individual nasal symptoms (p < or = 0.03) and TOSS (p = 0.011) versus placebo. The incidence of adverse events was similar for both treatment groups. MFNS, 200 mcg once daily, is an effective and well-tolerated treatment for symptoms of SAR in adolescents.