Childhood obesity and its consequences have been the subject of intense interest in recent years. In this study we examined the influence of overweight on circadian variations of ambulatory blood pressure (ABP) in Chinese adolescents. First, 24-hr ABP monitoring was performed in 252 adolescents divided into two groups with equivalent sex, age, and body height (49 girls and 77 boys in each group): controls (normal weight) were aged 13.68 +/- 1.21 years, height 165.37 +/- 9.45 cm, body mass index (BMI) 18.82 +/- 2.3; overweights (BMI > or = 24) were aged 13.71 +/- 1.23 years, height 165.75 +/- 9.47 cm, BMI 27.70 +/- 3.1. ABP recordings were treated by ABP database system and analyzed by cosinor method and conventional statistics methods. The circadian variations of ABP in adolescent patterned as "dipper" and circadian rhythmicity of ABP variations were confirmed by cosinor analysis in most adolescents of both groups. Significant statistical differences were found for rhythm parameters: the MESOR (midline estimate statistic of rhythm), peak, trough (the maximum and minimum values derived from the composed curves, respectively), and amplitude values between control and overweight groups. Significant higher values also were seen in the overweight group for most of ABP parameters (p < .01), such as, BP means (SBP, DBP, MAP: mean arterial pressure, or PP: pulse pressure), BP variability, BP loads and rate-pressure product (HR x SBP). Our results have shown that overweight influenced significantly on ABP and parameters derived from ABP recordings in Chinese adolescents, which suggests an increasing risk of cardiovascular diseases in overweight adolescents.