Amyloid Precursor Protein (APP) Intracellular Domain (AICD) is the product of APP processing realized by α- or β-secretases and γ-secretase. It was shown that AICD is able to interact with several proteins which regulate its stability and cellular localization. The Fe65 adaptor protein translocates AICD into nucleus where the APP-Fe65-Tip60 ternary complex may activate transcription of target genes. In the light of recent studies AICD seems to be another product of APP proteolysis endowed with important biological functions that may contribute to Alzheimer’s disease pathology.