The apolipoprotein E (APOE) gene has in many studies been identified as a susceptibility factor in Alzheimer's disease (AD). The APOE association is rather strong, but other not yet identified genetic factors are assumed to be involved in the pathogenesis of AD. Recently an association between an intronic polymorphism in presenilin-1 (PS-1) gene and late-onset AD was claimed. In order to confirm this observation we studied a sample of Polish patients with sporadic AD. However, our results did not confirm the existence of an association between the intronic polymorphism in the PS-1 gene and late-onset AD.