Five synthetic fragments of the N-terminal domain of the α7 subunit of the human nicotinic acetylcholine receptor (α7 nAChR) that correspond to theoretically calculated B epitopes and T helper epitopes of the protein and contain from 16 to 29 amino acid residues were tested for the ability to stimulate the formation of antibodies in mice of three lines having H-2d, H-2b, and H-2khaplotypes of the major histocompatibility complex. It was shown that, in the free (unconjugated) form, all the peptides stimulate the formation of antibodies at least in one mouse line. Most of the peptides induced the formation of antibodies in BALB/c mice (haplotype H-2d); therefore, more detailed studies were carried out on these animals. The free peptides and/or their conjugates with keyhole limpet hemocyanin were demonstrated to be capable of stimulating the formation in BALB/c mice of antibodies that bind to the recombinant extracellular N-terminal domain of (α7 nAChRα. The epitope mapping of antipeptide antibodies carried out using truncated fragments helped reveal antipeptide antibodies to four regions of the α7 subunit: 1-23, 98-106, 159-168, and 173-188 (or 179-188). © 2007 Pleiades Publishing, Inc.