Abstract Conduction system pacing (CSP) is increasingly accepted as an alternative to biventricular pacing in heart failure (HF) patients with left bundle branch block (LBBB) and non-LBBB. However, its efficiency in right bundle branch block (RBBB) is ill-defined. Herein, we report on the clinical outcomes of CSP in HFrEF patients with wide QRS complex and RBBB morphology. His-bundle (HBP) or LBB-area pacing (LBBAP) was attempted as a primary strategy in patients with RBBB, QRS duration ≥130 ms and left ventricular ejection fraction (LV EF) <35% and NYHA class II to IV HF despite optimized medical treatment for at least 6 months. Data on functional status, NT-pro-BNP levels and echocardiographic parameters were collected during follow-up and expressed as mean ± SEM, Statistical significance was calculated with Student’s paired t-test and chi square distribution. CSP was performed in 12 RBBB-HF patients (age 64.3±2.9 years) with mean QRS duration of 150±4 msec and baseline LV EF of 25.4±2.3%. The aetiology of HF was ischaemic (6 patients) and non-ischaemic cardiomyopathy (6 patients). During the procedure, HBP was achieved in 7 and LBBAP in 5 patients, resulting in a significant reduction in the QRS-duration (115±2.6 msec, P<0.0001) as compared with baseline value. CSP improved LV function (LV EF= 31.8±2.8%, P=0.009) as well as NYHA functional class (25% of the patients with NYHA II and 75% with NYHA III before vs. 33% with NYHA I, 33% with NYHA II and 33% with NYHA III after CSP, P=0.048) as compared to what was obtained prior to the procedure. A numerical decrease was also found in NT-proBNP levels (4735±2606 ng/ml before CSP vs. 3972±1883 ng/ml after CSP) which did not reach the level of statistical significance (P=0.45). In conclusion, CSP improved both quality of life and LV function in HFrEF patients with RBBB. Our results support the use of CSP in HFrEF patients with QRS width>130msec and RBBB morphology.