Right ventricular dysfunction (RVD) predicts poor survival in chronic heart failure (HF). Sex differences in RVD have been suggested but are still unraveled. We studied the influence of sex in the prognostic impact of RVD in chronic HF. We retrospectively analyzed adult ambulatory chronic HF patients with left ventricular systolic dysfunction (LVSD) followed from January 2012 to December 2020. Patients with no data on right ventricular function were excluded. Primary outcome: all-cause mortality; follow-up: January 2023. A Cox-regression analysis was used to determine the prognostic impact of RVD, adjustment for confounders was performed. Interaction between sex and RVD was tested. The analysis was stratified according to sex. We studied 1,152 patients, 65% male, mean age 71 years. RVD coexisted in 192 (17%). Patients with RVD were younger, more often presented atrial fibrillation and nonischemic HF, they had more severe LVSD, were more symptomatic, and presented higher BNP levels. During a median 44-month follow-up, 618 (54%) patients died. Patients with RVD presented higher all-cause mortality: multivariate-adjusted HR = 1.86 (1.26 to 2.76). When the analysis was stratified according to sex this negative prognostic impact was only present in females: multivariate-adjusted HR = 1.56 (1.02 to 2.39). The present of RVD was not prognostic associated in men. There was interaction between sex and RVD, p = 0.03. In conclusion, RVD appears to be associated with ominous outcome only in female patients: women with systolic HF with RVD presented a 56% higher risk of dying. In male HF patients, RVD showed no prognostic implications. Sex seems to influence the prognostic impact of RDV in chronic HF.