Weak-associated with wall cell peroxidases take part in determination potato resistance to bacterial infection. There are two strategy for protection potato cells under infection. Weak-associated with wall cell peroxidases of sensitive potato were activated 1.5–2 hours after infection. Peroxidases activity in the resistant potato roses sharply in the first minutes of infection. The increase of weak-associated with wall cell peroxidase activity of resistant potato in the first moments of infection is not related to protein synthesis and is apparently conditioned by the change of kinetic parameters.