Background: Data from National Health and Nutrition Examination Survey (NHANES) cycles 1988-1994 and 1999-2004 show a declining trend in the adherence to Dietary Approaches to Stop Hypertension (DASH) among adults. Since then, DASH evidence, dietary guidelines, and public-facing dietary resources have advanced, but whether national DASH adherence has improved is uncertain. Methods: We extended the Mellen et al. NHANES analysis among 14,163 adults with self-reported hypertension (N=6,914, 2003-2010, N=7,249, 2011-2018). DASH score included 9 nutrient components: total fat, saturated fat, protein, cholesterol, fiber, calcium, magnesium, potassium, and sodium, with adherence defined as a score 4.5. Survey-weighted multivariable models compared DASH score, adherence, and nutrient-threshold attainment across periods. Results: In 2011-2018, U.S. adults with self-reported hypertension represented 76.2 million individuals (33.8%). Multivariable-adjusted DASH adherence declined from 22.1% in 2003-2010 to 18.6% in 2011-2018 (p=0.003), and mean DASH score declined from 2.98 to 2.85 (p=0.007). Adjusted odds of adherence were lower in 2011-2018 compared with 2003-2010 (OR, 0.78; 95% CI, 0.67-0.91; p=0.002). Adherence was lower among non-Hispanic Black adults (OR, 0.70; 95% CI, 0.59-0.84), adults with BMI 30 kg/m2 (OR, 0.61; 95% CI, 0.51-0.73), and adults with prior stroke (OR, 0.71; 95% CI, 0.56-0.89). Total fat and sodium threshold attainment declined from 20.9% to 18.7% and 13.8% to 11.8%, respectively. Conclusions: DASH adherence among U.S. adults with self-reported hypertension declined from 2003-2011 to 2011-2018. Implementation strategies should identify barriers to adoption and address the full DASH dietary pattern.