Memory complaints are relatively common in elderly people, although they are not always reported to the general practitioner (GP). These subjective complaints do not necessarily correlate with objective measures of memory impairment or cognitive performance, but they may be an early indication of impairment at a state that is undetectable by standard testing instruments. Memory complaints may also predict future cognitive decline. The GuidAge study is a secondary prevention trial for Alzheimer's disease involving non-demented individuals aged 70 years or older having spontaneously complained of memory problems to their GP. More than half of participants had a Clinical Dementia Rating score of 0.5 at baseline. The percentage of participants reporting problems on the McNair and Kahn scale varied from 6.2% to 78.6% per item. Certain specific memory complaints may be more related than others to the beginning of the neurodegenerative process, and could predict future cognitive decline. The importance of memory complaints should not be underestimated in clinical practice.