Description: Objective Coiled-coil-helix-coiled-coil-helix domain containing 5 (CHCHD5), a mitochondrial protein, is involved in the oxidative folding process in the mitochondrial intermembrane space. A previous study identified a hypertension-related single nucleotide polymorphism (SNP), rs3748024, in CHCHD5 in adults, but there are no reports regarding the association between CHCHD5 and obesity, which is a known risk factor for hypertension. The aim of the present study is to investigate the associations of the SNP rs3748024 with hypertension and obesity. Design Cohort study. Setting Institute of Pediatrics in China. Participants We genotyped the SNP rs3748024 in the Beijing Child and Adolescent Metabolic Syndrome study. A total of 3503 children participated in the study. Primary and secondary outcome measures Genotyping of rs3748024 was conducted using the TaqMan Allelic Discrimination Assay. Lipids and glucose were analysed by an automatic biochemical analyser using a kit assay. The levels of adipocytokines (leptin, adiponectin and resistin) were measured by ELISA techniques. Results There was a statistically significant association between rs3748024 and systolic blood pressure (SBP) (β=–0.853, 95% CI –1.482 to –0.024, p=0.044) under an additive model adjusted for age, gender and body mass index (BMI) after correction for multiple testing. The SNP was also significantly associated with BMI (β=–0.286, 95% CI –0.551 to –0.021, p=0.043), obesity (OR=0.828, 95% CI 0.723 to 0.949, p=0.018) and triglycerides (β=–0.039, 95% CI –0.070 to –0.007, p=0.044) after correction for multiple testing. Conclusions We demonstrate for the first time that the SNP rs3748024 in CHCHD5 is associated with SBP, BMI, obesity and triglycerides in Chinese children. Our study identifies a new risk locus for hypertension and obesity in a child population. The function of CHCHD5 remains to be further studied to help elucidate the pathogenic role of CHCHD5 in hypertension and obesity.