ß-cryptogein, a proteinaceous elicitor from the phytopathogenic fungus Phytophthora cryptogea , is known to induce leaf necrosis in tobacco and non-specific resistance (expressed in the perinecrotic leaf area) against a wide range of tobacco pathogens, including Erysiphe cichoracearum . To reveal mechanisms underlying the induced resistance, biochemical changes in leaves of ß-cryptogein-elicited tobacco were followed up 3, 5 and 10 days after elicitation. The activity of peroxidase, ß-1,3 - glucanase and ß-glucosidase, as well as the patterns of acidic PR-proteins and isoperoxidases were determined. The protected part (perinecrotic area) and the non-protected part (distant extra-perinecrotic area) of leaves of ß-cryptogein - treated tobacco (Xanthi n.c.cv.) were analyzed. Leaves of water - treated tobacco served as controls. It was shown that in the protected leaf part ß-cryptogein caused significant metabolic shifts early after elicitation persisting during the whole period studied. An important increase of peroxidase and ß-1,3 - glucanase activity was recorded. PR1a and PR1b proteins, as well as new slow migrating isoperoxidase components appeared that were absent in the controls. Neglectable changes in ß-glucosidase activity were noticed. In the non-protected leaf part late and non-significant changes occurred. Taking into account the antimicrobial, regulatory and structure - consolidating properties of the biochemical components studied, it may be admitted that ß-cryptogein elicited the creation of a hostile environment, i.e. a basis of plant resistance against potential pathogens.