Disadvantaged adolescents are at higher risk for undiagnosed and untreated obesity and hypertension. Using nurse-measured weight, height, and blood pressure (BP) as well as self-reported age and activity/lifestyle behaviors, we assessed the prevalence of obesity and hypertension in 573 adolescent patients aged 13.0 to 17.9 years (females: n = 267, 46.6%; males: n = 306, 53.4%) from a clinic serving low-income, ethnically diverse pediatric patients. Body mass index distribution was as follows: 11, underweight (1.9%); 330, healthy weight (57.6%); 105, overweight (18.3%); and 127, obese (22.2%). The age-adjusted height percentile was normally distributed, but distribution by BP category was 326 normotensive (56.9%), 147 prehypertensive (25.7%), 60 with stage 1 hypertension (10.5%), and 40 with stage 2 hypertension (7.0%). Activity and lifestyle behaviors did not adequately explain obesity and hypertension rates. Efforts to prevent/reduce childhood overweight, obesity, and hypertension in underserved populations need to include dietary education, weight control interventions, and physical activity programs specifically tailored to overweight/obese youth and parents.