We screened 703 Australian subjects for an intronic polymorphism in the presenilin-1 (PS-l) gene. PS-l intronic allele 1 homozygosity was not associated with individuals with early-or late-onset sporadic Alzheimer's disease (EOAD or LOAD). Carriers for the PS-1 intronic allele 1 were also not associated with significantly increased risk for AD regardless of gender. Our results for the Australian population are consistent with those of recent reports for other populations and do not support the conclusion that the PS-I intronic polymorphism is associated with AD. (C) 1998 Elsevier Science Ireland Ltd.