Memantine, a moderate-affinity, uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, has been shown to be effective in dementia, including Alzheimer disease (AD). Therefore, its combination with acetylcholinesterase inhibitors (AChEIs) is anticipated. We report a postmarketing surveillance study conducted among German physicians who, during routine clinical practice, treated demented patients with memantine in combination with an AChEI. Most of the 158 surveyed patients (mean age, 74 years) were diagnosed with AD but other dementias were included. Memantine was prescribed at a wide range of daily doses (median, 20 mg/day) and was combined with donepezil for most patients (84%). Combination therapy was well tolerated for nearly all patients (98%) for an average observation period of 4 months at stable doses of both antidementia agents. No serious adverse drug reaction (ADR) was reported. No ADR or change in blood chemistry was experienced by most patients (96% and 81%, respectively); the six reported ADRs resolved without sequelae and without drug discontinuation. Global clinical status of most patients was judged as improved (54%) or stable (39%) over the observation period. These findings particularly suggest that memantine in combination with AChEIs is safe and well tolerated.