The aim of this study was to test the possible relationship between patterns of cognitive deficits--especially impairment of memory processes--and ApoE genotype in patients with AD. Fifty seven right-handed subjects (31 males and 26 females) were tested in this study. The age of subjects ranged from 50 to 79, the education lasted from 11 to 16 years. All subjects were diagnosed as probable AD patients on the basis of DSM IV and NINCDS-ADRDA criteria. Each subject was examined for: 1) ApoE genotype, 2) general level of activity (GDS and MMSE), 3) neuropsychological evaluation of cognitive processes, using full test battery. 37 patients had at least one of ApoE epsilon 4 allele (e2/4, 3 and 4/4) and 20 patients had none of ApoE 4 allele (e 2/3 and 3/3). The group of tested subjects were subdivided into 2 groups. The first group was comprised by 31 patients with 3-rd stage (according to GDS) of mental activity. Twenty six patients with 4-th stage were included into the second group. Those subgroups did not significantly differ if age, education, gender or ApoE allele were considered. Experimental data were normalized and then analyzed using a statistical package SPSS/PC+. The analysis of variance showed that the type of test, stage of disease and two-way interaction ApoE x type of test were highly significant (P < 0.0001). Some results were obvious and not surprising (e.g. that results of patients with 4-th stage were much worse than the results of patients with stage 3-rd). It turned out that the best results were obtained by our patients in naming tests, the worst--in learning test with distraction. Patients with ApoE epsilon 4 performed better than patients with none ApoE epsilon 4 in the Rey's test, in the similarity test and in the test which required repeating numbers starting from the last one. The differences between the subgroups of patients with different ApoE alleles were confirmed by different distributions of correlations. All statistical analyses were repeated for more homogenous group of patients (only with stage 3-rd). The pattern of results resembled the previous one (i.e. better performance in the same tests) with one exception: additionally, in delayed recall test patients with none ApoE epsilon 4 performed much better that ApoE epsilon 4. Our results showed that some cognitive processes depended on ApoE genotype. Patients with none ApoE epsilon 4 genotype had less severe deficits in delayed recall of new information. On the other hand, working memory appeared to be less affected in patients with ApoE epsilon 4 genotype. Independent of genotype, both group showed similar impairment of learning ability without deficits in remote memory.