Lupine diseases caused by pathogenic fungi constitute a serious problem in agriculture. They lead to partial yield loss and deterioration of crop quality through the changes in biochemical composition of seeds or their contamination with mycotoxins. Some of common lupine diseases are fusarioses caused by Fusarium oxyspomm f. sp. lupini. Morphometric and metabolic changes were investigated in yellow lupine seedlings infected with F. oxyspomm f. sp. lupini. It was found that infection caused temporary inhibition of seedling growth, overcome at later development, and activation of ß-glycosidase and peroxidases. The changes in enzymes activity indicate the induction of defense mechanism against F. oxyspomm f. sp. lupini and inhibition of pathogen spread.