Structural modification of flavone and flavanone, two weak inhibitors of aromatase, led to the new compounds 1-7, the syntheses of which are described as well as the evaluation of their aromatase and desmolase inhibitory potency. With the exception of 2 all compounds show a stronger inhibition of aromatase than the parent compounds and are more effective inhibitors than aminoglutethimide (AG), the only commercially available compound. In contrast to AG compounds 1 and 3-7 exhibit no desmolase inhibitory activity. In case of AG this effect leads to undesirable side effects.