Caregivers of demented patients are under significant stress along with physical, psychological or social problems. Standardized and validated instruments are required for measuring consequences of caregiving or efficacy of support interventions. Reliability of French translation of these instruments has to be verified in order to confirm their psychometric properties. The goal of the present study is to assess reliability of the French translation of three instruments designed for evaluation of caregivers of demented patients. The Zarit's Burden Interview (BI) is a 22-items scale measuring the subjective burden of the caregiver. The Revised Memory and Behavior Problems Checklist (RMBPC), a 53 item scale, measures frequency of memory and behaviour problems of demented patients and the caregiver's reaction to these problems, which is another mean of burden assessment. The Alzheimer's Disease Knowledge Test (ADKT) assesses knowledge of caregivers about demented diseases and resources available using 20 multiple choice questions. A reliability study was conducted on a sample of 40 caregivers. The caregivers were questioned twice, the second time after one (N = 26) or eight (N = 14) weeks. The BI internal consistency (Cronbach alpha) yielded a coefficient of 0.85 and test-retest reliability (intra-class correlation coefficient) was 0.89. The RMBPC's Cronbach Alpha was 0.93 for frequency and 0.94 for reaction. Intra-class correlation coefficients were 0.77 (frequency) and 0.90 (reaction) for RMBPC and 0.71 for ADKT.