Hereditary cerebral hemorrhage with amyloidosis—Dutch type (HCHWA-D) is a rare autosomal dominant disorder caused by an amyloid-β precursor protein (AβPP) 693 mutation that clinically leads to recurrent hemorrhagic strokes and dementia. The disease is pathologically characterised by the deposition of Aβ in cerebral blood vessels and as plaques in the brain parenchyma. This study measured the Aβ40 and Aβ42 concentration in plasma of Dutch AβPP693 mutation carriers and controls. We found that the Aβ40 concentration was not different between AβPP693 mutation carriers and controls. However, the Aβ42 concentration was significantly decreased in the mutation carriers. No correlation exists between the APOEε4 allele and the plasma of Aβ40 and Aβ42 levels in HCHWA-D patients. This finding contrasted with the increased concentrations found in Alzheimer's disease. Therefore it is suggested that the Dutch AβPP693 mutation located within the Aβ coding region of the AβPP gene has a different effect not only on clinical and pathological expression but also on Aβ processing.