OBJECTIVE: To examine the efficacy of a 3-month clinic-based behavioral nutrition intervention emphasizing a diet high in fruits, vegetables, and low fat dairy (DASH intervention) versus routine outpatient hospital-based nutrition care (RC) on diet and blood pressure (BP) in adolescents with elevated BP. STUDY DESIGN: Fifty-seven adolescents with a clinical diagnosis of prehypertension or hypertension (systolic BP or diastolic BP, 90(th) to 99(th) percentile) were randomly assigned to DASH or RC. SBP, DBP, 3-day diet recall, weight, and height were assessed at pretreatment, post-treatment, and 3 months later (follow-up). RESULTS: In completer analysis, DASH versus RC had a greater decrease in SBP z scores from baseline to post-treatment (P < 0.01) and a trend for a greater decrease in SBP z scores from baseline through follow-up (P = .07). DBP z scores changed similarly for conditions from baseline through follow-up. Relative to RC, DASH had a greater increase in intake of fruits (P < .001), potassium and magnesium (P < .01), and a greater decrease in total fat (P < .05) from baseline to post-treatment. From baseline through follow-up, DASH versus RC had a greater increase in low fat dairy (P < .001). CONCLUSIONS: The DASH intervention proved more effective than RC in improving SBP and diet quality in adolescents with elevated BP.