Fourteen peptides corresponding to sequences of all the exposed and some of the transmembrane protein regions of porin A from the outer membrane of Neisseria meningitidis strain B: 15:P1.7,16 were synthesized. Mice of various lines were immunized with the free peptides not conjugated with any protein carrier. It was shown that the majority of the peptides possess immunogenic properties. Two peptides were identified binding to antibodies present in the serum of mice after meningitis. Protective properties of a number of the synthesized peptides were studied, and three peptide sequences inducing mice protection to an experimental infection with N. meningitidis were identified. © 2000 MAIK "Nauka/Interperiodica".