Being an informal caregiver of patients with chronic diseases may imply significant psychological burden and suffering, potentially harmful to caregiver's own physical and mental health and patient's recovery. Little is known about the psychosocial experiences and characteristics of caregivers of patients with Implantable Cardioverter Defibrillator (ICD), mainly in the Brazilian population, so that the purpose of the present study (transversal descriptive quantitative) was to characterize, both demographically and psychosocially, a nonprobabilistic sample of informal caregivers of patients with ICD undergoing treatment in a university hospital in the interior of the State of São Paulo. The studied variables comprised: sociodemographic characteristics, life quality, anxiety, depression and perception of burden. Sixty caregivers took part in the survey, and they were interviewed between September, 2010 and May, 2011. Data collection used the following instruments: Semi-structured Interview Script prepared for this survey, SF-36 Health Evaluation Questionnaire, Hospital Anxiety and Depression Scale and the Zarit Burden Interview. Data was analyzed quantitatively in a descriptive way. Subsequently, statistically significant association (p≤0,05) was verified between some variables of interest through Fisher's Exact Test. Results describe that the average age of caregivers was 52.5 years (DP=14.76), they were mostly female (n=45, 75%), and patient's spouses (n=39, 65%), predominantly with up to four years of education (n=28, 46.67%), and most (45, 75%) with health problems. Twenty-five caregivers (41.67%) presented symptoms related to anxiety and 13 (21.67%) to depression. In life quality evaluation, the highest average score was in the Social Aspects dominion (Average=78.12, DP=27.48) and the lowest in Vitality (Average=60.25, DP=26.03). The average score regarding burden perception was of 19.93 (DP=12.51, Median= 18.5). Participants reported significant changes in their lives after ICD implant, concerns about patient's health and device operation, difficulties concerning their role as caregivers, in addition to doubts about the implantable defibrillator. Results confirm that the ICD implant had a significant impact in the life of their informal caregivers, requiring provision of emotional support by healthcare professionals in order to help them adapt and properly cope with these situations. Due to the scarcity of Brazilian studies in this population and some limiting methodological factors, further investigation is required to compare these results.