10-Deoxoartemisinin at 0.2 mg ml(-1) medium was transformed to 7beta-hydroxy deoxoartemisinin by Mucor ramannianus growing on sucrose, 20 g l(-1), and peptone, 10 g l(-1), at pH 4 and 26 degreesC. The yield of product was increased from 16% to 45% by selecting optimal culture conditions using a 2(5-2) factorial design.