This study was undertaken to evaluate the effect of galanthamine, a new cholinesterase inhibitor on cognitive performances in 84 patients with various apoE genotype and Alzheimer's disease (AD) during the six-month treatment. The diagnosis of AD was made on the basis of NINCDS/ADRDN criteria. ApoE4 genotype was determined by PCR procedure. The cognitive performance was assessed MMSE at baseline and six months later. The difference among the groups was statistically analyzed by ANOVA model and Pearson's chi2-test. The MMSE at baseline in all completes was 18.0 +/- 3.73, whereas the mean value of MMSE after 6 months was 16.4 +/- 5.61 indicating significant deterioration (p < 0.01). Of the 84 patients, 14 (169%) were apoE4 homozygous, 41 (49%) were heterozygous, whereas 29 (35%) were apoE4 negative. The significant number of responders was observed among apoE4 homozygous patients (71%; chi2 = 6.89; p = 0.032). The subgroup of apoE4 homozygous patients with AD in its mild to moderate stage may be considered as responders to galanthamine.