Fusarium moniliforme var. subglutinans was selected from among 100 strains of fungi for producing ginsenoside F-1 from ginsenoside Rg(1). The enzyme responsible was purified as a single 85 kDa band with a specific activity of 136 U mg(-1). It hydrolysed glucose-linked ginsenosides Rb-1, Rd and Rg(1) but not for other monosaccharide-linked ginsenosides, Rb-2, Rc, R-1, and Re. Under the optimum conditions of pH 6.0, 50A degrees C, 30 U l(-1) of enzyme, and 5 mg Rg(1) ml(-1), 4 mg F-1 ml(-1) was produced after 4 h, with a molar yield of 100% and a productivity of 1 g l(-1) h(-1). This represents the highest productivity and conversion yield of F-1 yet reported.