The effects produced by the addition of sterol synthesis inhibitors on the artemisinin content of the transgenic organ culture (A. tumefaciens ATCC 33970 or 15955) of Artemisia annua are presented. The transgenic tissue produced 3-4 fold higher levels of artemisinin 0.84% (56.3 mg/L) within a short culture period compared with field grown plants (0.23%). The addition of the sterol synthesis inhibitors, miconazole and terbinafine, to these transgenic cultures resulted in enhanced artemisinin content up to 1.15% and 1.44%, respectively. Further enhancement of artemisinin content was achieved by varying the addition time of the sterol synthesis inhibitor to the cultures. The best artemisinin content (2.62%) was observed after terbinafine (10 mg/L) addition on the sixteenth day of the culture period.