Hypertension and obesity in children are increasing concerns worldwide. A cross-sectional study of hypertension in relation to overweight/obesity was conducted in 2009 among schoolchildren aged 6–16 years in Aden, Yemen. Using multistage stratified random sampling 1885 children were classified into wasted, normal weight, overweight and obese according to body mass index. The prevalence of wasting was 10.1%, normal weight 69.2%, overweight 12.7% and obesity 8.0%. The rate of high blood pressure (World Health Organization criteria) was 8.2% for prehypertension and 2.4% for hypertension and was significantly related to the presence of overweight or obesity. Child’s body mass index combined with age was a predictor for systolic and diastolic blood pressure. The study provides further evidence that overweight/obesity is associated with hypertension in these schoolchildren.