Abstract BACKGROUND Family caregivers in neuro-oncology (e.g., spouse, family member, friend to a patient) have high unmet support needs, yet intervention trials and effective support options are scarce. The Response Assessment in Neuro-Oncology (RANO-) Cares working group investigated the methodological quality of neuro-oncology caregiver outcomes reporting in randomized controlled trials (RCTs). METHODS A systematic review was performed to evaluate to what extent RCTs assessing outcomes of caregivers of adult primary brain tumor patients adhere to minimum reporting standards. A 33-item checklist (23 applicable to secondary analysis reports) based on the International Society for Quality of Life Research (ISOQOL) criteria for patient-reported outcome (PRO) reporting was used. Risk of bias was assessed per RCT. RESULTS Fifteen publications from 11 unique RCTs included 676 neuro-oncology caregivers, with low overall risk of bias. Ten publications (66%) reported on caregiver outcomes as a primary aim, of which eight (80%) satisfied ≥2/3 of the key methodological criteria. Of the five secondary analysis reports (33%) two (40%) met ≥2/3 of applicable key criteria. Criteria often not reported adequately included sample size calculations (reported adequately in n=8, 53%), participant flow (n=9, 60%) window for data collection (n=1, 6%), and extent of (n=10, 66%), reasons for (n=9, 60%), and statistical approaches in dealing with (n=4, 26%) missing data. CONCLUSION Whilst there are opportunities to enhance reporting standards, RCTs that include neuro-oncology caregiver outcomes generally adhere to high quality reporting standards, and have low risk of bias, indicating good potential to impact clinical practice.