OBJECTIVES To assess the prevalence of prescribed medications with anticholinergic activity given concurrently with acetylcholinesterase-inhibitor therapy in long-term care residents with dementia and to recommend dose adjustment or discontinuation of these medications with anticholinergic activity. DESIGN Prospective case series. SETTING Long-term care facilities in Indiana. PATIENTS Geriatric residents in long-term care facilities were included if they were receiving both an agent with anticholinergic activity as determined by radioreceptor assay and an acetylcholinesterase inhibitor. INTERVENTIONS Recommendations were made to the resident's physician suggesting substitution, dose reduction, or discontinuation of the agent with anticholinergic activity. MAIN OUTCOME MEASURES The number of residents with a recommended change in their anticholinergic medication regimen as a result of the consultant pharmacist's recommendation. RESULTS Of the 2,021 long-term care residents evaluated, 498 (25%) were receiving an acetylcholinesterase inhibitor. Of the 498 residents receiving acetylcholinesterase inhibitor therapy, 103 (20.7%) were receiving concurrent medications with anticholinergic activity. The most commonly prescribed medication with anticholinergic activity was furosemide, an agent with "possible" or low anticholinergic effects. One hundred forty-six medications with anticholinergic activity were used in these 103 residents. Overall, adjustments to the agents with anticholinergic activity were completed in 24 (16.4%) cases. The majority of medications prescribed had "possible" anticholinergic activity (62.3%) compared with those prescribed with "definite" anticholinergic activity (37.7%). No medication dose adjustments or discontinuations were frequent, regardless of whether the medication was deemed to have "definite" (29.1%) or "possible" (31.9%) anticholinergic activity. Medication changes or discontinuations occurred in 13 (23.6%) agents with "definite" and 11 (12.1%) agents with "possible" anticholinergic activity. CONCLUSIONS Medications with anticholinergic activity may interfere with the beneficial effects of acetylcholinesterase inhibitors. Attention should be placed, however, on agents with moderate or strong anticholinergic activity or the use of multiple medications with anticholinergic activity. Health care providers should consider the risk versus benefit of using agents with anticholinergic activity in someone with cognitive impairment receiving an acetylcholinesterase inhibitor.