Introduction: Atrial fibrillation is the most common arrhythmia encountered in clinical practice. It is associated with increased morbidity and mortality, due to the risk of thromboembolic events and associated risk factors. The purpose of the study was to analyze the clinical characteristics of very elderly patients (>80 yo) with permanent atrial fibrillation admitted in the Internal Medicine Clinic of Bucharest University Emergency Hospital over a period of one year. Methods: The total number of admissions in 2013 was 3,470. From these, 273 patients were over 80 years old (7.86%); 195 had permanent atrial fibrillation and represented our study group. We analyzed data from the hospital record database. Results: The distribution by sex in the study group: 81 men (41.53%) and 114 women (58.46%). The mean age was 84.5 yo. 42.56% of the patients were institutionalized in nursing homes. The main comorbidities were: arterial hypertension 78.46%, coronary artery disease 61.02%, heart failure 47.17%, chronic obstructive pulmonary disease 44.61%, peripheral artery disease 42.05%, cerebrovascular disease 40.51%, valvular heart disease 39.48%, diabetes 31.79%, dementia 14.35%, chronic kidney disease (eGFR <60 ml/min./1.73 m2 ) (MDRD) 9.74%. As compared to non-institutionalized patients, those residing in nursing homes were older and had higher comorbidity score. In-hospital mortality rate in very elderly patients with atrial fibrillation was 10.76%. Conclusions: Atrial fibrillation is a frequent arrhythmia in very elderly patients. Very elderly patients with atrial fibrillation have many comorbidities, arterial hypertension, coronary artery disease, heart failure and chronic obstructive pulmonary disease being the most frequent. In-hospital mortality rate of very elderly patients with atrial fibrillation is high. Adequate control of arterial hypertension and management of heart failure in patients with atrial fibrillation, alongside with stroke prevention are key priorities for the management of very elderly patients with atrial fibrillation and improving quality of their life.