AIMS: Patients with end-stage heart failure (HF) often require surrogate decision making for end-of-life care owing to a lack of decision-making capacity. However, the clinical characteristics of surrogate decision making for life-sustaining treatments in Japan remain to be investigated. METHODS AND RESULTS: Among 934 patients admitted to our hospital for HF from January 2004 to December 2015, we retrospectively reviewed the medical records of consecutive 106 patients who died in hospital (mean age 73 ± 13 years; male, 52.6%). During hospitalization, attending physicians conducted an average of 2.1 ± 1.4 end-of-life conversations with patients and/or their families. Only 4.7% of patients participated in the conversations and declared their preferences; surrogates made medical care decisions in 95.3% of cases. Most decisions by surrogates (98.1%) were made without the patient's advance directive. During initial end-of-life conversations, 49.4% of surrogates requested cardiopulmonary resuscitation (CPR). However, 72.0% of CPR preferences were changed to do not attempt resuscitation (DNAR) orders in the final conversation. Female surrogates were more likely to change the preference from CPR to DNAR than were male surrogates (47.1% vs. 25.0%, P = 0.023). CONCLUSIONS: Compared with male surrogates, female surrogates wavered more often in their decisions regarding life-sustaining treatments of Japanese patients with end-stage HF.