Neuronal loss is one of the major pathological hallmarks of neurodegenerative disorders including Alzheimer's disease (AD). Using rigorous quantitative methods, the distinct pattern of neuronal loss in pathological conditions such as neurodegeneration and in normal aging was clearly shown. Furthermore, the decrease of total neuronal numbers correlated in a considerable extent with the presence of neurofibrillary degeneration in the same brain regions. However, it appears that neurofibrillary tangles are not the only cause of reduction of neuronal populations, but also alternative triggers could induce neuronal death in this disease. Various inducers, most probably, activate different cell death pathways. Recently, apoptosis has been implicated as a possible mechanism for neuronal death. There is essentially no evidence of apoptosis in AD that would meet all criteria of its classical definition. Therefore it was suggested, that other modes of cell death could contribute to neuronal loss in AD and related disorders (Tab. 2, Ref. 70).