Background: Increased jugular venous pressure, reflecting the increased right atrial pressure, is a classical sign of heart failure (HF) but clinical assessment may be difficult. Methods: In ambulatory patients with HF and control subjects, jugular vein diameter (JVD) was measured using a linear high-frequency ultrasound probe (10 MHz) at rest, during a Valsalva manoeuvre and during deep inspiration. JVD ratio was calculated as diameter during Valsalva to that at rest. Results: 211 patients (mean age 70 years; mean left ventricular ejection fraction 43%) and 20 controls were included. JVD (median and inter-quartile [IQR] range) at rest was 0.17 (0.15–0.20) cm in controls and 0.23 (0.17–0.33) cm in patients with HF (p = 0.012), JVD ratio was 6.3 (4.3–6.8) in controls and 4.4 (2.7–5.8) in patients with HF (p = 0.001).With increasing quartiles of plasma NT-proBNP, JVD at rest rose (0.20 (0.15–0.23) cm, 0.21 (0.16–0.29) cm, 0.25 (0.18–0.35) cm and 0.34 (0.20–0.53) cm (P =