Sunflower and other Helianthus ssp. produced, among other secondary metabolites, the coumarins scopoletin, scopolin and ayapin. In the most general sense they can be defined as stress metabolites, their synthesis being induced in response to adverse environmental condition, both biotic and abiotic. The pattern of coumarin synthesis and accumulation depends on plant variety, it is tissue dependent and developmentally regulated. Coumarin synthesis in sunflower seems to be part of the defence strategy against microorganisms, insect and parasitic plants. From an agricultural point of view the defensive potential of these compounds can be exploited in order to develop resistant varieties (either by classical plant breeding or by biotechnology) or crop protection strategies involving the use of chemicals which induced coumarin synthesis