Background Acute heart failure is a life-threatening clinical condition. Levosimendan is an effective inotropic agent used to maintain cardiac output, but its usage is limited by the lack of evidence in patients with severely abnormal renal function. Therefore, we analyzed data of patients with acute heart failure with and without abnormal renal function to examine the effects of levosimendan. Methods We performed this retrospective cohort study using data from the Chang Gung Research Database (CGRD) of Chang Gung Memorial Hospital (CGMH). Patients admitted for heart failure with LVEF ≤ 40% between January 2013 and December 2018 who received levosimendan or dobutamine in the critical cardiac care units (CCU) were identified. Patients with extracorporeal membrane oxygenation (ECMO) were excluded. Outcomes of interest were mortality at 30, 90, and 180 days after the cohort entry date. Results There were no significant differences in mortality rate at 30, 90, and 180 days after the cohort entry date between the levosimendan and dobutamine groups, or between subgroups of patients with an estimated glomerular filtration rate (eGFR) ≥ 30 mL/min/1.73 m2 and eGFR