Alzheimer's disease (AD), the most common presenile dementia is underdiagnosed in Poland, thus every attempt to make the frequency of this diagnosis approaching standards of Western countries should be recommended. Deposits of beta A4 amyloid in a form of amyloid (senile) plaques, diffuse amyloid deposits and congophilic angiopathy is central to the pathogenesis of AD. These amyloid deposits are virtually invisible in routine pathological stainings like HE but may be visualized with Bielschowsky silver impregnation, other metallic impregnations, and following Thioflavine S or Congo red stainings. We report here that amyloid deposits are as easily immunolabeled with commercially available antibodies against beta A4 (DAKO) and such a staining was greatly enhanced by microwave oven pretreatment. In all cases of AD, the diagnosis could be easily made using either 4GM or commercial DAKO anti-beta A4 antibodies following pretreatment with formic acid or processing in microwave oven. Pretreatment in microwave oven even for only one second was already sufficient to visualize beta A4-immunopositive plaques while after 5 second the intensity of staining approached that obtained after formic acid pretreatment.