Background: Developing accurate identification methods for individuals with suicide attempts and providing them with follow-up care and supports can be a vital component of all comprehensive suicide prevention strategies. However, because of the difficulties concerning one’s intentions behind injurious behaviour, identifying suicide attempts is a challenge for families and clinicians. Objectives: The aim of this study was to investigate the differences between family report and clinical assessment for suicide attempts in the emergency department (ED). Methods: A total of 148 patients with suspected suicide attempts (SSAs) and 148 family caregivers in the ED were enrolled. The suicide risk module of the Chinese version of the MINI International Neuropsychiatric Interview and the self-report measure were used to assess those with SSA’s suicidal behaviours. The Family Adaptability and Cohesion Evaluation Scales and semi-structured interviews were used to investigate the characteristics of suicide risk and demographics of patients with SSA, as well as the rate and influencing factors of omitted suicide attempts reported by family caregivers. Results: The underreporting rate for family reported suicide attempts in the ED was 69.0%. The suicide attempts group indicated lower mean scores on perceptions of family resources, adaptability and cohesion. Patients' suicide risk rating (OR =−1.81, 95% CI: −3.87 to −0.33, p=0.036), family satisfaction (OR =−1.11, 95% CI: −2.29 to −0.06, p=0.048), and caregiver’s age (OR =−1.68, 95% CI: −3.10 to −0.48, p=0.010) might be associated with underreporting by families. If patients committed suicide attempts through a falling injury or medication overdose, their families may have misreported the suicide attempt. Conclusions: The discordance of suicide attempt records between family report and clinical assessment reveals the limitations of family self-reports when identifying suicide attempts. Interviews and observations, together with information from certain diagnoses, should be combined to accurately identify suicide attempters in the ED.