To assess the clinical characteristics and management of patients with atrial fibrillation (AF), we performed a prospective survey of all acute medical admissions over six months to our hospital. Of 7,451 such admissions, 245 had AF (110 male, 135 female; mean age 74.4 years). Of these, 213 were Caucasian, 10 black/Afro-Caribbean and 22 Asian. Complete data were available for 185 patients. Of these, 82 had newly diagnosed AF, 83 had previous chronic AF and 20 had paroxysmal AF. The main presenting features was dyspnoea, stroke and syncope. A history of ischaemic heart disease was present in 64, heart failure in 46, hypertension in 51 and rheumatic heart disease in 13, while 31 had a previous stroke. Chest X-ray showed cardiomegaly and pulmonary oedema in 121 patients, but was normal in 28. Echocardiography showed poor cardiac function in eight patients and enlarged left atria in five. Only 28% of those with previously diagnosed AF were on anticoagulation. Of the newly diagnosed patients, only 18% were started on anticoagulants. Cardioversion was attempted or planned in only 6%. The primary diagnosis on discharge was heart failure in 45, stroke in 24 and myocardial infarction in 12. AF remains a common arrhythmia among acute medical admissions and is commonly associated with heart failure and a high mortality. There is still a reluctance to start anticoagulant therapy or to perform cardioversion in such patients.