The correlates of dropout, efficacy, and adverse events in the tratment of Alzheimer's disease (AD) with acetylcholinesterase inhibitors (ChEI) are unclear. To investigate these issues, a 26-week prospective, randomized, open-labeled trail with donepezil or rivastigmine was undertaken. Sixty-four Korean patients with AD were recruited, and data on sociodemographic and clinical characteristics and several assessment scales were collected. Characteristics of available caregivers were also gathered. Information on adverse events and dropout was recorded. Thirty-five (55%) patients dropped out during treatment with ChEI, for reasons mainly related to financial burden of caregivers. Of the 29 patients who completed the 26-week trial, 16 (55%) were responsive to ChEI. Lower scores on the Clinical Dementia Rating and Blessed Dementia Scale at baseline were associated with the efficacy of ChEI. Of the total participants, 26 (41%) experienced adverse events, although these seemed to be mild and appeared to be associated with the psychological state of patients or coadministration of psychotropic drugs. In conclusion, ChEI seemed to be effective and well tolerated in the treatment of Korean patients with AD, but the use of this drug was limited mainly by the financial burden of caregivers.