This is a short fragment of the b-Amyloid peptide containing Histidine 13 and 14. Alzheimer’s beta amyloid peptides form Ab ion channels in lipid bilayers. It is postulated that ion channel activity of Ab is related to cytotoxic activity of Ab. Small peptides that contain the amino acid sequence of the predicted mouth region of the Ab channel pore can inhibit Ab ion channel activity. Histidines 13 and 14 have been shown to be essential for the peptide to inhibit Alzheimer’s disease Ab ion channel and cytotoxicity.