Abstract Background Iron deficiency is a major problem in heart failure (HF) patients. Although the negative impact of iron deficiency on left ventricular (LV) function is known, the effect on right ventricle function (RV) is unclear. In this study we aimed to investigate the effect of iron deficiency on RV function. Material and Methods A hundred patients hospitalized with acute decompensated HF (ADHF) regardless of LV ejection fraction (LVEF) were included in our study. The primary outcome was association between iron deficiency and TAPSE, RVEF, RV FAC, and RV TDI S’. The secondary outcome was impact of iron deficiency on RV free wall global longitudinal strain (GLS). Results The mean age of study population was 70±10 years-old and 64% were male. The prevalence of hypertension (HT), diabetes mellitus (DM), ischemic heart disease (IHD), chronic obstructive pulmonary disease (COPD) was 80%, 52%, 71%, and 18%, respectively. While the median LVEF was 35%, the proportion of patients with reduced EF (HFrEF), mildly-reduced EF (HFmrEF), and preserved EF (HFpEF) was 66%, 6% and 28%, respectively. On transthoracic echocardiography the median TAPSE was 16.4 mm, the mean FAC %37,2±7.8, the mean RV GLS %-16.4±5.1, and the mean RV TDI S’ was 10.6±2,9 cm per second. More than half of the patients (58%) had iron deficiency. There was no difference between patients with or without iron deficiency on neither demographics nor LVEF, RV FAC, RV TDI S’ and systolic pulmonary artery pressure (sPAP). The TAPSE (15.6 vs 17.2 mm, p = 0.05) and RV free wall GLS (-14.7% vs -18.2%, p = 0.005) was lower in HF patient with iron deficiency. Anemia was present in 56% of the patients and both TAPSE (15.3 vs 17.3 mm, p = 0.01) and RV GLS (-14.7% vs -18.6%, p = 0.01) were lower in patients with anemia. Conclusion RV dysfunction accompanying LV dysfunction adversely affects the prognosis. In patients with ADHF, iron deficiency causes subclinical RV dysfunction namely decreased RV free wall GLS before the right ventricle systolic functions parameters commonly used on echocardiography (RVEF, TAPSE, RV FAC, RV TDI S’) in daily practice deteriorate. In conclusion, screening for iron deficiency in HF patients facilitates early detection and treatment of iron deficiency which prevents RV dysfunction with iron replacement.Table 1Table 2