Late-onset depressive disorder (LOD) is thought to be associated with dementia. Allele 1 in the presenilin-1 (PS-1) gene is a risk factor for Alzheimer's disease. An association study on this polymorphism was performed in depressive patients and control subjects. The patients were subdivided into those with early onset and late onset, using 50 years as the cut-off age. There was no statistically significant difference in the age of onset of depressive disorders according to the PS-1 genotype. There was also no association between early/late-onset depressive disorders and the PS-1 genotype. Our results suggest there is no association between the PS-1 allele and LOD.