Among the biologically important roles of isoflavones is also their effect on carcinogenesis. We used flow injection analysis and high performance liquid W with electrochemical detection to simultaneously determine certain isoflavones (biochanin A, formononetin, sissotrin, daidzin, daidzein, glycitin, glycitein and genistein). The most suitable chromatographic conditions were: mobile phase: 0.2 mol L-1 acetate buffer (pH 5.0); flow rate 2.0 mL min(-1); column and detector temperature: 26 degrees C; detection potential: 800 mV. Under the optimal conditions, the detection limits were in the range of several ng mL(-1). Their simultaneous determination takes 15 min