Objective. The aim of this study was to investigate the psychometric properties of the Family Inventory of Resources for Management (FIRM) in a sample of family caregivers of cancer patients. Methods. In this methodological study, construct validity of the FIRM was evaluated by known groups and convergent validity in a convenience sample of family caregivers of cancer patients (n=104) referred to the outpatient oncology wards of five educational hospitals in Tehran from January to April 2016. Reliability was determined by assessing the internal consistency and stability of the instrument. Results. The known-groups findings showed that there is a significant difference between the scores of the FIRM in family caregivers with different levels of caregiver burden (p<0.001). Also, the results of convergent validity showed that there is a moderate negative correlation (r=-0.50; p<0.001) between the total scores of the FIRM and the scores of the caregiver burden inventory (CBI). The FIRM showed a good internal consistency (α=0.85) and a good stability of the test-retest reliability result. Conclusions. There is a sound psychometric basis for the use of the Persian translation of the FIRM for family studies in the Iranian population.