Aims: The prognostic value of the right ventricular parameters in patients with heart failure (HF) is well documented, but the data on patients undergoing mitral valve repair are lacking. Methods and results: The association between pre-operative right ventricular dilatation and outcome was studied in 70 consecutive patients with HF who underwent elective mitral valve repair. Mean age was 67 years, 71% were men, mean pre-operative NYHA class was 2.8, mean pre-operative ejection fraction was 31%, and 47% had atrial fibrillation. The ischaemic cardiomyopathy (ICM) was the cause of HF in 32% of the patients. Perioperative mortality was 7.1% by a median logistic Euroscore of 7.5 (range 1.3-47.5). During a mean follow-up of 887 days, 35% of the patients reached the combined endpoint of overall mortality or transplantation. Reoperation was performed in four patients. One and 3 years survival rates were 88% and 72%, respectively. By multivariate Cox analysis, right ventricular dilatation, ICM, and age significantly predicted the outcome. Conclusion: Right ventricular dilatation is an important modulator of outcome in patients with HF and mitral regurgitation.