© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. OBJECTIVE: To examine the prevalence, correlates and sociodemographic inequalities of undiagnosed hypertension in Nepal. DESIGN: This study used cross-sectional 2016 Nepal Demographic and Health Survey (NDHS) data. Undiagnosed patients with hypertension were defined as an NDHS respondent who was diagnosed as hypertensive (systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg) during the survey, but never took any prescribed anti-hypertensive medicine to lower/control blood pressure and was never identified as having hypertension by a health professional prior the survey. Multiple binary logistic regression analysis was performed, and Concentration Index was measured.Nepal. PARTICIPANTS: Adult patients with hypertension. RESULTS: Among 3334 patients with hypertension, 50.4% remained undiagnosed during the survey in Nepal. Adjusted model reveals that patients who were male, belonged to households other than the highest wealth quintile, and lived in province 4 and province 5 were at higher risk of remaining undiagnosed for hypertension. Patients who were ≥65 years of age and were overweight/obese were at lower risk of remaining undiagnosed for hypertension. The poor-rich gap was 24.6 percentage points (Q1=64.1% vs Q5=39.6%) and poor:rich ratio was 1.6 (Q1/Q5=1.6) in the prevalence of undiagnosed hypertension. Undiagnosed hypertension was disproportionately higher among lower socioeconomic status groups (Concentration Index, C=-0.18). Inequalities in the prevalence of undiagnosed hypertension further varied across other geographic locations, including place of residence, ecological zones and administrative provinces. CONCLUSIONS: Undiagnosed hypertension was highly prevalent in Nepal and there were substantial inequalities by sociodemographics and subnational levels. Increasing awareness, strengthening routine screening to diagnose hypertension at primary health service facilities and enactment of social health insurance policy may help Nepal to prevent and control this burden.