We studied caregivers’ willingness-to-pay for Alzheimer’s disease drug therapy. We recruited 216 caregivers of persons with mild or moderate Alzheimer’s disease and presented them with four scenarios describing a hypothetical Alzheimer’s disease medication. The scenarios described the medication as capable of either treating the symptoms of disease or modifying the course of disease. The scenarios also presented two different probabilities of adverse effects occurrence, i.e. 0% or 30%. Most caregivers said they would pay out-of-pocket for the medication, with support for such payment ranging from 68% to 93%, depending on the specific scenario. The highest level of support was for the ‘disease modifying and no adverse effects’ scenario, while the lowest level was for the ‘symptom treatment and 30% chance of adverse effects’ scenario. On average, caregivers’ monthly willingness-to-pay out-of-pocket for the medication ranged from $214 to $277 (Canadian dollars). Dollar amounts were highest for the ‘disease modifying and no adverse effects’ scenario and lowest for the ‘symptom treatment and 30% chance of adverse effects’ scenario. Support for out-of-pocket payment and specific dollar amounts were highest when the medication did not involve adverse effects. Caregivers placed more value on the absence of adverse effects than on drug efficacy.