In the present study, we aimed to verify associations between ambulatory blood pressure (ABP) and pediatric obstructive sleep apnea (OSA) in a hospital-based population. This was a cross-sectional observational study on children aged 4 to 16 years with OSA-related symptoms from a tertiary referral medical center. All children received overnight polysomnography and 24-hour recording of ABP. Severity of the disease was classified as primary snoring (apnea-hypopnea index, AHI <1), mild OSA (AHI 1-5), and moderate-to-severe OSA (AHI >5). For 195 children enrolled in this study (mean age, 7.8 ± 3.4 years; 69% boy), ABP increased as severity of OSA increased. During daytime, children with moderate-to-severe OSA had significantly higher systolic blood pressure (BP) (117.0 ± 12.7 vs 110.5 ± 9.3 mmHg), mean arterial pressure (MAP) (85.6 ± 8 .1 vs 81.6 ± 6.8 mmHg), and diastolic BP load (12.0 ± 9.6 vs 8.4 ± 10.9 mmHg) compared with children with primary snoring. During nighttime, children with moderate-to-severe OSA had significantly higher systolic BP (108.6 ± 15.0 vs 100.0 ± 9.4 mmHg), MAP (75.9 ± 9.6 vs 71.1 ± 7.0 mmHg), systolic BP load (44.0 ± 32.6 vs 26.8 ± 24.5 mmHg), systolic BP index (0.5 ± 13.1 vs -6.8 ± 8.5 mmHg), and higher prevalence of systolic hypertension (47.6% vs 14.7 %) compared with children with primary snoring. Multiple linear regression analyses revealed an independent association between AHI and nighttime systolic BP and MAP after adjusting for adiposity variables. This large hospital-based study showed that children with moderate-to-severe OSA had a higher ABP compared with children who were primary snorers. As elevated BP in childhood predicts future cardiovascular risks, children with severe OSA should be treated properly to prevent further adverse cardiovascular outcomes.