Amyloid beta-peptide (Abeta) deposition in brain is important in the development of Alzheimer's disease (AD). Neprilysin (NEP) appears to be the major Abeta degrading enzyme in vivo and reduced mRNA levels of NEP correlates with increased plaque density. We hypothesized that alterations in the NEP promoter region may alter NEP expression and thus be involved in the AD process. We investigated three putative important regions in the NEP promoter region; two dinucleotide-repeats (CA and GT) and a 480 base pair fragment. With fragment analysis and sequencing, 164 early-onset and 152 late-onset Swedish AD cases and 109 non-demented controls were investigated. No significant difference in the distribution of promoter polymorphisms between AD cases and controls were found in this study.