OBJECTIVES: Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice with increasing prevalence in the aging population. The objective of our study was to evaluate the impact of AF on secondary care costs in Scotland. METHODS: Patient hospitalisation data collected by the Information and Statistics Division (ISD) of the Scottish National Health Service (NHS) from 2004 to 2008 were analysed to estimate the trends in hospital episodes in the 5.2 million population of Scotland. The associated costs were estimated using the tariff prices in Scotland for the respective years. RESULTS: Over the 5 year period, the number of patients hospitalised for AF increased by 21.0% to 26,510 patients in 2008 from 21,907 in 2004, with a total of 162,449 hospital admissions for AF over this period and accounting for 20.8% of total cardiovascular (CV) hospitalisations in 2008.  The total inpatient bed days in 2008 were 394,128; a 14.5% increase during this time, with mean length of inpatient stay for AF higher than the mean for all cardiovascular conditions (10.9 vs 8.7).  The total cost (inpatient and day cases) attributable to AF increased from £138.9 million in 2004 to £162.5 million in 2008, accounting for a quarter (23.8%) of all CV hospital costs in Scotland. Overall, the burden of AF was higher among women and increased progressively with age. CONCLUSIONS: AF presents a significant and increasing burden on hospital care in Scotland. As a proportion of total CV burden, AF accounts for nearly a quarter and is increasing at a relatively higher rate.