The psychopathological structure and prognostic significance of mild cognitive impairment syndrome (MCI) were studied in a two-year prospective study of randomized cohorts of elderly subjects whose mental state corresponded to the criteria for MCI. A total of 40 patients aged from 50 to 80 years were studied. Patients underwent clinical history-taking, neuropsychological, psychometric, and genetic investigations (genotyping for ApoE), as well as brain imaging studies. The psychopathological structure and psychometric characteristics of MCI syndrome are presented. Clinical and genetic factors with prognostic significance are identified.