OBJECTIVES: To evaluate the HRQoL and burden of family caregivers of dialysis patients, and to analyze which variables were associated to it. METHODS: A sample of 221 patient-carer pairs, stratified by age and gender, was randomly selected from 14 dialysis units: 152 patients were on hemodialysis and 69 on peritoneal dialysis. Patients and carers answered the SF-36, obtaining Physical(PCS) and a Mental(MCS) Component Summary scores standardized by age and gender, and the Duke-UNK Functional Social Support(FSS). Carers also answered the Caregiver Burden Interview of Zarit(ZS). RESULTS: Mean PCS and MCS scores of carers were 48.4±13.8 and 48.0±11.3 respectively.Multiple regression analysis showed that the variables associated to lower PCS of the carer were:higher ZS and older patient age(R2=0.15; p<0.001).Variables associated to lower MCS were:higher ZS and lower FSS of the carer,and lower MCS of the patient(R2=0.29;p<0.001).Variables associated to a higher ZS of carers were: lower FSS and lower PCS and MCS scores of the carer and higher age and lower PCS and MCS scores of the patient(R2=0.49;p<0.001).Carers with a MCS=<42 points(cutoff point associated with depression) were 28.3% (95%CI=22.4-34.8).Logistic regression analysis showed that variables associated to having a MCS=<42 points were: higher ZS and lower FSS of carer. CONCLUSIONS:The HRQoL of caregivers is slightly worse than that of the general population of the same age and gender. Physical health status is more damaged in those caregivers suffering greater burden and caring for older patients, and mental health status is more damaged in those suffering greater burden, feeling lower social support and caring for patients with worse mental health status.The burden experienced by family carers depends on perceived social support, age of patient and physical and mental health status of carer and patient. A significant percentage of carers have depression which is associated to greater burden and lower social support perceived.