BACKGROUND: It is not clear whether Emergency Severity Index (ESI) is valid to triage heart failure (HF) patients and if HF patients benefit more from a customized triage scale or not. The aim of study is to compare the effect of Heart Failure Triage Scale (HFTS) and ESI on mistriage among patients with HF who present to the emergency department (ED). METHODS: A randomized clinical trial was conducted from April to June 2017. HF patients with dyspnea were randomly assigned to HFTS or ESI groups. Triage level, used resources and time to electrocardiogram (ECG) were compared between both groups among HF patients who were admitted to coronary care unit (CCU), cardiac unit (CU) and discharged patients from the ED. Content validity was examined using Kappa designating agreement on relevance (K*). Reliability of both scale was evaluated using inter-observer agreement (Kappa). RESULTS: Seventy-three and 74 HF patients were assigned to HFTS and ESI groups respectively. Time to ECG in HFTS group was significantly shorter than that of ESI group (2.05 vs. 16.82 minutes). Triage level between HFTS and ESI groups was significantly different among patients admitted to CCU (1.0 vs. 2.8), cardiac unit (2.26 vs. 3.06) and discharged patients from the ED (3.53 vs. 2.86). Used resources in HFTS group was significantly different among triage levels (H=25.89; df=3; P<0.001). CONCLUSION HFTS is associated with less mistriage than ESI for triaging HF patients. It is recommended to make use of HFTS to triage HF patients in the ED.