Background: We explored carer motivation for seeking participation for a relative in an Alzheimer's disease (AD) clinical drug trial, to assess impressions of the value of trial participation. We also surveyed the carers of patients who did not meet study entry screening criteria to see if our conduct of the screening visit was acceptable and ethical. Method: A retrospective questionnaire was sent to the carers of 36 randomized participants and 22 carers of patients who did not meet study entry screening criteria for an AD clinical treatment trial. Results: Twenty-nine (81%) of the trial participant carers and 15 (68%) of carers of the group who did not meet study entry criteria returned their questionnaires with sufficient information for analysis. The prime motivators in seeking trial participation were to help their relative feel better and live longer, to contribute to medical science, to improve the health of others, and the hope of a cure. Carers of both groups found research staff supportive and would recommend trial participatiion to others. Conclusions: Even though trial participation is onerous and patients were generally perceived by carers as not having improved, both the screening visit and participation in the trial itself were seen as positive experiences and the expectations of carers were met.