36 patients who presented with mild cognitive impairment (MCI) (memory loss and a Minimental test de Folstein (MMT) of 25-30) had previously been followed up for 31 months: 15 developed Alzheimer dementia, 11 got better (they suffered from emotional disorders) and 10 remained as MCI. In this study we describe an additional follow-up period of two years of the ten patients who persisted with MCI. Five developed dementia (Alzheimer type with or without a vascular component). One got better, one developed a progressive supranuclear palsy, and only 3 remained as MCI. This clinical experience leads us to conclude that it is difficult to differentiate between MCI and emotional disorders in the elderly The second point is that MCI usually represents the prodromal phase of Alzheimer disease. There are two final comments. The first is that the diagnosis of Alzheimer disease could be considered in patients without dementia; the second one, that early diagnosis of MCI may allow the use of drugs which might postpone or even prevent dementia