This study examined 1-year persistency with cholinesterase inhibitors (ChEIs) for the treatment of elderly Alzheimer's dementia (AD) patients in Korea. Korean Health Insurance Review & Assessment Service database from January 2005 to June 2006 was used. Patients aged 65 or older with AD diagnosis who were first prescribed a ChEI were included. The 1-year persistence, persistency rate, and switching patterns during the follow-up period were identified. Mean time to drug discontinuation was analyzed, and persistency rates between different patient factors were compared. The 1-year persistency rate of newly treated 6,461 AD patients was 24.0%, while 50% of study patients discontinued treatment by 91 days from initiation. Persistency rates of female patients (22.8%), patients in rural areas (12.7%), and primary care (10.2%) were relatively low (p < 0.001). Persistency rate differed between age groups (p < 0.001). Overall proportion of switching was 6.6%. The 1-year persistency rate of ChEIs for AD patients in Korea did not reach those of previous researches in other countries. Patients less likely to remain on therapy should be especially monitored to optimize treatment persistence.