<p>This study aimed to compare prevalence, clinical features, and outcomes between patients with heart failure (HF) with preserved ejection fraction (HFpEF) and those with reduced ejection fraction (HFrEF) who received anticancer drugs. This single-center, retrospective study included 126 patients who developed new-onset HF or worsening HF after starting anticancer drug treatment between April 2018 and December 2023. HFrEF was defined as HF symptoms and signs with left ventricular ejection fraction (LVEF) &lt; 50%, and HFpEF as LVEF ≥ 50%. Among the cohort, 49 patients (39%) had HF with New York Heart Association functional class ≥ 3, and the proportions of HFrEF and HFpEF were similar (61 [48%] vs. 65 [52%], respectively). Patients with HFrEF had a significantly higher history of anthracycline use, whereas fluoropyrimidine or other cytotoxic chemotherapy use was lower. Overall, 84% discontinued or interrupted anticancer therapy after HF onset. There were no significant differences in overall survival (log-rank p = 0.27) or cancer treatment continuation rates (log-rank p = 0.83) between HFpEF and HFrEF. All-cause mortality was associated with anemia (odds ratio [OR]: 3.46, 95% confidence interval [CI]; 1.36–8.82, p = 0.009) and performance status ≥ 3 (OR: 3.13, 95% CI; 1.18–8.26, p = 0.021), but not with LVEF. In patients who developed HF after anticancer treatment, HFrEF and HFpEF occurred at similar rates. There were no significant differences in overall survival or cancer treatment continuation between groups. Anemia and poor performance status, but not LVEF, independently predicted all-cause mortality.</p> Graphical Abstract <p></p>